Allylsilanes

4.4.40 Product Subclass 40: 

Allylsilanes 

T. K. Sarkar 

General Introduction 

Scattered information regarding this product subclass can be found in Houben±Weyl, 

Vol. 13/5. A comprehensive review covers the literature on methods for the preparation 

of allylsilanes up to early 1990. [1,2] Currently, many patents are available for allylsilanes. 

[3±8] 

Allylsilanes are one of the most useful organosilicon reagents and are widely used in 

either addition±elimination reactions or annulation reactions. More importantly, unlike 

other allylmetal reagents, allylsilanes can be used as intermediates as well, since they can 

survive a large number of chemical transformations. The use of allylsilanes in organic 

synthesis has been extensively described in several excellent monographs [9±13] and numerous 

review articles. [14±30] 

The addition reaction of allylsilanes with carbonyl compounds was first carried out 

on activated substrates, such as chloral and chloroacetone in the presence of aluminum 

trichloride or gallium(III) chloride as Lewis acid. [31,32] The pioneering example of the intramolecular 

reaction of allylsilanes containing an acetal function took place in the presence 

of tin(IV) chloride. [33] The scope of these allylation reactions was greatly expanded 

when it was found that titanium(IV) chloride promotes regioselective addition of allylsilanes 

to nonactivated carbonyl groups in high yield. Thus, cyclopentanone undergoes 

1,2-addition with allyltrimethylsilane (1) to give homoallyl alcohol 2, [34] whereas hexahydronaphthalen-2-one 

gives the 1,4-addition product 3 [35] (Scheme 1). Therefore, these 

reactions are useful in organic synthesis [see Science of Synthesis, Vol. 36 (Alcohols) and 

Science of Synthesis, Vol. 26 (Ketones)]. 

Scheme 1 Allylation of Carbonyl Compounds with an Allylsilane [34,35] 

1 

SiMe3 

FOR PERSONAL USE ONLY 

O 

H 

O 

44% 

85% 

, TiCl4 

, TiCl4, CH2Cl2 

The influence of the geometryof the double bond in allylsilanes was first observed in the 

reaction of but-2-enylsilanes with aldehydes. For example, the allylation reaction of (E)but-2-enyltrimethylsilane 

[(E)-4] with pivalaldehyde is highly syn selective (syn-5/anti-5 

>99:1); in contrast, selectivityis lower for the Z-isomer (Z)-4 (Scheme 2). [36] 

Sarkar, T. K., SOS, (2002) 4, 837. 2002 Georg Thieme Verlag KG 

HO 

O 

2 

3 

H 

837 

for references see p 920

Scheme 2 Diastereoselective Reactions of E- and Z-But-2-enylsilanes [36] 

(E)-4 

SiMe 3 

SiMe3 (Z)-4 

+ Bu t CHO 

TiCl4 

(syn-5/anti-5) >99:1 

OH 

t Bu 

+ 

TiCl4 + ButCHO syn-5 

(syn-5/anti-5) 65:35 

Titanium(IV) chloride has also been used widelyas the Lewis acid of choice to promote the 

reactions of allylsilanes with other electrophiles including epoxides, acetals, iminium 

ions, and acid chlorides. 

An allylsilane with silicon-centered chiralityshows a low level of chiralitytransfer in 

its Lewis acid mediated reactions with aldehydes and acetals. [37] However, when a stereogenic 

center is in one of the substituents on the silyl group, good asymmetric induction 

has been observed, for example, the formation of 6 in 47% ee (Scheme 3). [38] 

Scheme 3 Asymmetric Induction in a Lewis Acid Mediated Allylation Reaction [38] 

MeO 2C 

N 

SiMe 2 

+ PrCHO 

TiCl 4 

OH 

6 47% ee 

Besides titanium(IV) chloride, other catalysts such as tin(IV) chloride, the boron trifluoride±diethyl 

ether complex, ethylaluminum dichloride, trimethylsilyl trifluoromethanesulfonate, 

iron(III) chloride, bismuth(III) bromide, [39] Amberlyst 15, and so forth have also 

found use in the reactions of allylsilanes. 

The allylation reaction of aldehydes with allylsilanes generally requires stoichiometric 

or greater amounts of Lewis acid because of tight binding of the product homoallyl alcohol 

to the Lewis acid catalyst, as well as poor efficiency of silicon transfer to oxygen. A 

catalytic version of this reaction is possible if 2±10 mol% of scandium(III) triflate is used; 

thus, if a stoichiometric amount of acetic anhydride is used in the allylation reaction, 

homoallylic acetates can be prepared in an essentially one-pot reaction, for example, the 

formation of 7 (Scheme 4). [40] 

Scheme 4 Catalytic Allylation of Aldehydes with a Scandium(III) Triflate Catalyst [40] 

1 

SiMe3 

+ PhCHO 


838 Science of Synthesis 4.4 Silicon Compounds 

Sc(OTf) 3 (cat.) 

Ac2O (2 equiv) 

74% 

Allylation reactions of allylsilanes can also be carried out under nucleophilic conditions 

(TBAF, KF, or NaOMe). Fluoride ion induced reaction of carbonyl compounds with allylsilanes 

generallytakes place readilyat room temperature. With á,â-unsaturated esters, 

nitriles, and amides as substrates, reactions of allyltrimethylsilane in the presence of fluoride 

ion occur exclusively in a 1,4-fashion, while Lewis acid catalyzed processes yield no 

addition products at all. [20] 

Allyltris(trimethylsilyl)silanes react by a free-radical chain mechanism with organic 

halides, therebyeffecting a net replacement of the halide bya propenyl group if the polar 

Ph 

OAc 


7 

Bu t 

OH 

anti-5

matching of both partners is appropriate [41] [see Section 4.4.40.57 and Science of Synthesis, 

Vol. 47 (Alkenes)]. 

The reactivityof allylsilanes can be suitablytuned byvariation of the ligands on the 

silicon atom. The use of a large number of examples of allylsilanes containing pentacoordinated 

silicon have also been described in the literature. [22,27,42] The principle of 

strain-induced Lewis acidity is beautifully demonstrated in the stereoselective reactions 

of allylsilane (E)-8 and (Z)-8 with an aldehyde (Scheme 5); no catalytic activation is needed 

here, where the stereoselection implicates a cyclic transition structure. [43] 

Scheme 5 But-3-enols from Thermal Allylation of Aldehydes [43] 

Pr 

Pr 

(E)-8 

(Z)-8 

Si 

Si 

Ph 

Ph 

+ PhCHO 

+ PhCHO 


4.4.40 Allylsilanes 839 

1. 130 oC 2. H + 

68% 

1. 130 oC 2. H + 

66% 

Lewis acid promoted [3 +2] and [2+2] annulation of stericallyhindered allylsilanes and 

subsequent oxidative cleavage of the carbon-silicon bond provide hydroxycyclopentanes 

and hydroxymethylcyclobutanes [44,45] (see Section 4.4.40.69). 

In general, allylsilanes are thermally stable and relatively inert to moisture and air. 

Theyare storable and can be handled without special precautions. Onlya few thermally 

labile allylsilanes, which require storage at low temperature, are known. [46] Allylsilanes 

are stable to chromatographyon silica gel or Florisil; it is rare to see the addition of a little 

triethylamine to the eluent to avoid acid-catalyzed decomposition on the column being 

recommended. [47] On the other hand, allylhalosilanes are moisture sensitive and therefore 

care should be taken to prevent hydrolysis during storage. 

Allyltrimethylsilane is nontoxic; other allylsilanes are also expected to be so, with 

the exception of allylhalosilanes. The main dangers with the latter may arise from hydrolysis 

products such as hydrogen halides. 

Allylsilanes have a C=C stretching band which appears in the approximate range of 

í = 1600±1660 cm ±1 in their infrared spectra; the E configuration of 3-substituted allylsilanes 

can be ascertained from a band of medium intensityat approximatelyí = 965± 

990 cm ±1 . 29 Si NMR is a powerful technique for determining the structure of silicon-containing 

compounds. [48] 

Synthesis of Product Subclass 40 

4.4.40.1 Method 1: 

From Allylmagnesium Halides and Trialkylhalosilanes 

Allylsilanes are available from allyl halides by silylation of the corresponding Grignard 

reagents with an appropriate chlorosilane. This route works best for simple and symmetrical 

alk-2-enylsilanes, for example, 9, or those having a considerable steric and/or electronic 

bias, for example, 10 (Scheme 6). [49±52] Regio- and stereocontrolled synthesis of allylsilanes 

bythis conventional method is not, however, an easytask in view of well-known 

stereorandomization of the allylmetallic intermediates. [53] 


Ph 

Ph 

OH 

Pr 

OH 

Pr 

+ 

5:95 

+ 

95:5 

Ph 

Ph 

OH 

Pr 

OH 

Pr 


In some cases, especiallywith 3,3-disubstituted allylsilanes, the problem can be obviated 

by the generation of allyl Grignard reagents with high stereochemical purity, by direct 

insertion of highlyreactive Rieke magnesium into the allylic carbon-halogen 

bonds at verylow temperature (±958C); this is shown, for example, bythe formation of 

(E)- and (Z)-11 with remarkable regio- (á/ã > 99:1) and stereoselectivity(Scheme 6). [54] However, 

for monosubstituted allylsilanes, such as dec-2-enyltrimethylsilane, this method is 

not suitable, and use of the corresponding allyllithium intermediate is recommended for 

high regio- and stereoselectivity. [54] 

Scheme 6 Allylsilanes from Allylmagnesium Halides and Chlorotrimethylsilane [50,52,54] 

Cl 



9 

SiMe3 

1. Mg 

Cl SiMe 

2. TMSCl 

3 

10 

1. Rieke Mg, −95 o Cl 

C 

2. TMSCl 

80% 

SiMe3 (E)-11 (E/Z) >99:1:

pressure. Flash chromatography(silica gel, pentane/Et 2O 20:1) gave the product as a colorless 

oil; yield: 5.33 g (97%); bp 134±1358C/0.22 Torr. 

4.4.40.1.2 Variation 2: 

Silylation of an In Situ Generated Grignard Reagent 

The addition of an allyl halide to a suspension of magnesium metal and chlorotrimethylsilane 

in tetrahydrofuran yields the corresponding allylsilane, for example, in the preparation 

of 13 and 14 (Scheme 8). [56,57] This reaction is believed to involve the in situ generation 

of the allylmagnesium halide, which reacts with the trialkylhalosilane by displacement. 

Scheme 8 Silylation of an In Situ Generated Grignard Reagent [56,57] 

Cl 

( )n 

X 

TMSCl, Mg 

Cl Me3Si SiMe3 

TMSCl, Mg, THF 

X = Cl; n = 1 94% 

X = Br; n = 2 54% 



Cyclopent-2-enyltrimethylsilane (14, n = 1); Typical Procedure: [56] 

A mixture of TMSCl (55.33 g, 0.51 mol), Mg (18.5 g, 0.77 mol), and THF (250 mL) was cooled 

to 58C in an ice bath. An addition funnel was charged with a soln of 3-chlorocyclopentene 

(52.27 g, 0.51 mol) in THF (500 mL), and cooled with a dry-ice jacket. The resulting cooled 

soln was added dropwise to the stirred mixture over several hours. The mixture was allowed 

to warm to rt, and then stirred overnight. It was washed with H 2O (5 ” 100 mL), 

and the aqueous washings were back-extracted with pentane (50 mL). The combined organic 

phases were washed with brine (100 mL), dried, and concentrated under reduced 

pressure; yield: 67.1 g (94%); bp 140±1468C/760 Torr. 

( ) n 

14 

13 

SiMe 3 

4.4.40.2 Method 2: 

From Allylmagnesium Halides by Transition-Metal-Catalyzed Coupling 

with Hydrosilanes 

E-But-2-enylsilanes are available by nickel-catalyzed coupling of but-2-enylmagnesium 

bromide with hydrosilanes. The most effective catalyst for this reaction is [1,1¢-bis(diphenylphosphino)ferrocene]dichloronickel(II) 

[NiCl 2(dppf)], which is used in the preparation 

of 15 (Scheme 9). [1,58] Of note is the requirement of a large excess of the Grignard reagent 

for the yield to be good and for the regio- and stereoselectivity to be high. For some 

simple allylsilanes, such as allyltris(4-methoxyphenyl)silane, the yield of product by this 

protocol is higher than bythe Grignard method. [55] 

Scheme 9 Preparation of E-But-2-enylsilanes [1,58] 

R 1 R 2 2SiH 

MgBr SiR 

15 

1R2 NiCl2(dppf) (cat.) 

R 

2 

1 = Me; R2 = Ph 85%; (E/Z) 98:2 

R1 = Ph; R2 = Me 72%; (E/Z) 98:2 

[(E)-But-2-enyl]dimethylphenylsilane (15,R 1 = Ph; R 2 = Me); Typical Procedure: [1,58] 

[NiCl 2(dppf)] (13.6 mg, 0.02 mmol) was placed in a two-necked flask equipped with a magnetic 

stirring bar and a three-waystopcock. After evacuation, the flask was filled with N 2 

and was cooled to 08C. To it was added a soln of 0.54 M but-2-enylmagnesium bromide in 



Et 2O (37 mL, 20 mmol) followed byMe 2PhSiH (136 mg, 1.0 mmol). The mixture was stirred 

at rt for 69 h and then hydrolyzed with 10% aq HCl. The organic layer and the Et 2O extracts 

from the aqueous layer were combined, washed with sat. aq NaHCO 3 and H 2O, and 

dried (MgSO 4). Removal of the solvent under reduced pressure followed bybulb-to-bulb 

distillation of the residue gave 15 (R 1 = Ph; R 2 = Me) containing 2% Z-isomer; yield: 

137 mg (72%). 

4.4.40.3 Method 3: 

From Allyl Chlorides by Zinc-Mediated Silylation 

Allylsilanes have been prepared by the treatment of alkyltrichlorosilanes with an equimolar 

amount of allyl chloride in the presence of zinc powder in 1,3-dimethyl-2-imidazolidinone 

(DMI) as solvent, for example, in the formation of allylchlorosilanes 16 (Scheme 

10). [59] Use of at least 2 equivalents of 1,3-dimethyl-2-imidazolidinone is recommended, 

otherwise the yields are lower. In some cases, such as allylation of trichlorohexylsilane 

or trichlorophenylsilane, no more than 2 equivalents of 1,3-dimethyl-2-imidazolidinone 

should be used, as excess 1,3-dimethyl-2-imidazolidinone is rather difficult to separate 

from the product. The zinc-mediated allylation reaction can also be applied to dichlorodimethylsilane 

and chlorotrimethylsilane. [59] A notable feature of this protocol is the selective 

formation of dichloro(methyl)(1-methylallyl)silane 16 (R 1 =R 2 = Me) from (E)-1-chlorobut-2-ene, 

since silylation of but-2-enyl Grignard reagents invariably gives a regio- and 

stereoisomeric mixture of allylsilanes [53] (see Section 4.4.40.1). 

Scheme 10 From Allyl Chlorides by Zinc-Mediated Silylation [59] 

R 1 

Cl 



R 2 SiCl 3, Zn, DMI 

R1 = H; R2 = Me 69% 

R1 = H; R2 = iPr 60% 

R1 = R2 = Me 69% 

R 1 

16 

SiR 2 Cl 2 

Allyl(dichloro)methylsilane (16, R 1 =H;R 2 = Me); Typical Procedure: [59] 

A mixture of DMI (100 mL), Zn powder (13.0 g, 0.2 mol), and MeSiCl 3 (29.4 g, 0.2 mol) was 

placed in a 200-mL three-necked flask. The mixture was subjected to a N 2 purge and heated 

to 70 8C. Allyl chloride (15.0 g, 0.2 mol) was added dropwise to the mixture over 5 min. 

After the addition, Et 2O was added and the precipitated salts were filtered off. The mixture 

was then heated for another 1 h, and the product was isolated bydistillation under 

reduced pressure; yield: 21.4 g (69%). 

4.4.40.4 Method 4: 

From Allyl Halides by Electroreductive Synthesis 

Allyl halides undergo electrochemical reduction in the presence of a silylating agent in a 

solution of tetraalkylammonium salt in dimethylformamide to give allylsilanes, for 

example, the preparation of cyclohex-2-enyltrimethylsilane (14, n = 2; Scheme 11). [60] 

The regiochemical outcome of these reactions depends both on the steric properties of 

the silylating agent as well as the electronic properties of the allyl moiety. [61] This method 

tolerates the presence of some reactive groups in the substrate, as in, for example, the 

selective formation of (4-bromocinnamyl)trimethylsilane (17). [61] Additionally, it also allows 

the synthesis of certain functionalized (difluoroallyl)silanes, for example, silane 19 

from the corresponding chlorodifluoromethyl-substituted enol ether 18; note that this reaction 

succeeds in spite of the low labilityof a chlorine atom in a chlorodifluoromethyl 

moiety. [62] In addition to halides, an acetoxygroup also serves as a leaving group for this 

reaction, [61] but onlyin the presence of tetrakis(triphenylphosphine)palladium(0) as catalyst. 

[63] 

Sarkar, T. K., SOS, (2002) 4, 837. 2002 Georg Thieme Verlag KG

Scheme 11 From Allylic Halides by Electrochemical Synthesis [60±62] 

Br 

Cl 

EtO 

F 

18 

F 

Ph 

TMSCl, 2 e 

Br 

67% 

SiMe3 Cl 

TMSCl, 2 e 

94% 

TMSCl, 2 e 

49% 

Me3Si 

EtO 

19 

14 n = 2 

(2-Ethoxy-1,1-difluoro-3-phenylallyl)trimethylsilane (19); Typical Procedure: [62] 

The reaction was conducted in a cylindrical undivided cell, fitted with a Mg rod as anode 

and a Ni foam cathode under argon. Enol ether 18 (3.95 g, 17 mmol) and freshlydistilled 

TMSCl (8.7 mL, 68 mmol) were added to a soln of DMF (50 mL) containing TBAB (100 mg, 

0.3 mmol). The electrolysis was performed under a constant current (i = 0.06 A) until no 

more starting material was left. After extraction with Et 2O, the organic phases were 

washed with 1 M HCl and brine and dried (MgSO 4). Solvents were removed under reduced 

pressure, and after filtration (silica gel, pentane/Et 2O 95:5) of the residue, pure silane 19 

was obtained as a colorless liquid; yield: 4.36 g (94%). 

4.4.40.5 Method 5: 

By Silylation of Metalated Alkenes 

Allylsilanes are available bydirect metalation of alkenes, followed bysilylation with trialkylhalosilanes. 

Two procedures are followed: in one butyllithium is used, often in the 

presence of a chelating amine, for example, N,N,N¢,N¢-tetramethylethylenediamine, to 

generate allyllithium species, while, in the other, Schlosser s base (butyllithium and potassium 

tert-butoxide) is used to generate allylpotassium intermediates for subsequent 

silylation. 

4.4.40.5.1 Variation 1: 

From Lithiated Alkenes 



Silylation of lithiated alkenes generated by deprotonation of alkenes with butyllithium in 

the presence of N,N,N¢,N¢-tetramethylethylenediamine gives allylsilanes. The regioselectivityof 

this reaction depends on the deprotonation site of the alkene and the selectivity 

of attack of the allyllithium species on the halosilane. For methylenecyclobutane, a mixture 

of allylsilanes, for example, 20 and 21, forms, with the latter slightlyfavored 

(Scheme 12). [64] This method is suited for the preparation of a varietyof terpenic allylsilanes, 

for example, silane 22. [65] 

Alkenes containing a hydroxy group are also amenable to this procedure. [66±70] For example, 

allylsilane 24 (n = 1) was prepared from alcohol 23 (n = 1) where a large excess of 

butyllithium was needed for success; here alkoxide coordination at allyllithium appears 

to be essential for facile C-silylation, which does not occur when n = 2 or 3. [66,67] 

F 

F 

Ph 

Br 

17 

SiMe 3 



Scheme 12 Allylsilanes from Lithiated Alkenes [64±67] 

H 

OH 

( ) n 

H 

23 

1. BuLi, TMEDA, hexane, rt 

2. TMSCl, −78 oC, 4 h 

1. BuLi, TMEDA 

2. TMSCl 

58% 



1. BuLi, TMEDA 

2. TMSCl 

3. MeOH, H2O 

60% 

22 

SiMe3 

H 

20 

SiMe3 

OH 

( )n 

H 

24 

+ 

40:60 

SiMe3 

SiMe3 21 

(Cyclobut-1-enylmethyl)trimethylsilane (20) and 

Trimethyl(2-methylenecyclobutyl)silane (21): [64] 

Methylenecyclobutane (1.36 mL, 14.7 mmol) was added to a stirred soln of TMEDA (0.86 g, 

1.2 mL, 7.4 mmol) and BuLi (7.4 mmol) in hexane (3 mL) under argon. After the soln had 

stirred at rt overnight, hexane (2±3 mL) was added. 

The alkenyllithium (118 mmol), prepared as above, was cooled to ±788C, and TMSCl 

(distilled from Bu 3N; 21.6 mL, 146 mmol) was added rapidly. The soln was stirred for 4 h, 

then poured into H 2O, and extracted with Et 2O. The Et 2O layer was washed with H 2O (2 ”), 

dried (MgSO 4), filtered, and concentrated in vacuo to yield a pale green oil, which on distillation 

(bp 1308C/760 Torr) gave 20 and 21 (20/21 2:3); total yield: 12.68 g (77%, based on 

alkenyllithium). 

4.4.40.5.2 Variation 2: 

From Alkenylpotassium Compounds 

Z-Allylsilanes can be prepared by the deprotonation of an alk-1-ene or alk-2-ene with 

Schlosser s base, and subsequent treatment of the allylmetal intermediate with a halosilane. 

[71±77] Allylsilanes 12 (R 1 = t-Bu; R 2 = Me) and (Z)- and (E)-25 have been prepared bythis 

protocol (Scheme 13). [72,73] Of note is complete or predominant retention of alkene configuration 

in products (Z)- and (E)-25. Bytrapping of the allylpotassium intermediate with a 

halosilane immediatelyafter its formation, it was shown that (Z)-but-2-ene leads to an 

endo-alkyl-substituted allylpotassium intermediate, while the exo-alkyl intermediate results 

from (E)-but-2-ene. [73±75] However, the allylpotassium intermediate may undergo torsional 

isomerization under thermal or catalytic conditions, so that the thermodynamicallystronglyfavored 

endo intermediate forms, no matter whether an alk-1-ene, a Z-orE-alk- 

2-ene, or even a mixture of such isomers are used as starting materials, and silylation then 

results in Z-allylsilanes. [71,72,74,76] In this way, a range of terminal allylsilanes, for example, 

allylsilane 26, has been prepared with more than 95% Z selectivity. [72] The presence of a 

free hydroxy group on the carbon backbone is compatible with this procedure; in such a 

case, 2 equivalents of the superbasic reagent are needed, as well as pent-1-ene as catalyst, 

to effect stereohomogenization of the allylpotassium intermediate; an example of this is 

the preparation of silane 27. [76] The reason for endo selectivityis not clear at present. [74] A 


similar protocol starting with but-3-enyltrimethylsilane yields (Z)-allylsilanes with substituents 

at the 3-position. [78] 

Scheme 13 Allylsilanes from Alkenylpotassium Compounds [72,73,76] 

( ) 4 

HO ( )5 

1. BuLi, t-BuOK 

2. TBDMSCl 

77% 

SiMe 2Bu t 

12 R 1 = t-Bu; R 2 = Me 

BuLi, t-BuOK M TIPSCl SiPr i 3 

BuLi, t-BuOK 



1. BuLi, t-BuOK, THP 

2. TMSCl 

70% 

M 

( ) 4 

1. t-BuOK, BuLi, THP, −25 to 0 oC, 2 h 

2. pent-1-ene, 25 oC, 50 h 

3. TMSCl, −25 to 25 oC 55% 

TIPSCl 

26 

SiMe 3 

(Z)-25 

(E)-25 

SiPr i 3 

HO ( ) 5 SiMe 3 

Trimethyl[(Z)-oct-2-enyl]silane (26); Typical Procedure: [72] 

At ±258C, precooled THP (20 mL), oct-1-ene (6.3 mL, 4.5 g, 40 mmol), and t-BuOK (4.5 g, 

40 mmol) were consecutivelyadded to BuLi (20 mmol), from which the commercial solvent 

(hexane) had been stripped off. After 3 h of vigorous stirring at 0 8C, the mixture 

was kept at ±258C (deep freezer) for 72 h. After the addition of TMSCl (4.9 mL, 4.2 g, 

40 mmol) at ±758C, the mixture was allowed to reach 258C under stirring before being 

poured into H 2O (25 mL). The aqueous phase was extracted with Et 2O (2 ” 20 mL). The combined 

organic layers were washed with brine (2 ” 10 mL), dried, and concentrated. The 

product (Z/E 95:5, byGC) was obtained after distillation of the residue; yield: 2.6 g (70%); 

bp 28±30 8C/0.3 Torr. 

[(Z)-8-Hydroxyoct-2-enyl]trimethylsilane (27): [76] 

At ±258C, precooled THP (50 mL), oct-7-en-1-ol (2.2 mL, 25 mmol), and t-BuOK (8.4 g, 

75 mmol) were added to BuLi (50 mmol) from which the commercial solvent (hexane) 

had been stripped off. After the mixture had stirred for 2 h at 0 8C, pent-1-ene (1.1 mL, 

10 mmol) was added to the bright red soln, which was then kept for 50 h at ±258C before 

being treated with TMSCl (9.5 mL, 75 mmol). When the mixture had reached 258C, it was 

vigorouslyshaken with 6 M HCl (25 mL), washed with H 2O (2 ” 25 mL) and brine (25 mL), 

and concentrated. Distillation of the residue gave the product as a colorless liquid; yield: 

2.8 g (55%); bp 85±89 8C/1 Torr. 


27 


4.4.40.6 Method 6: 

From Metalated Allyl Halides and Chlorotrimethylsilane 

Silylation of metalated allyl halides, generated from allyl halides and lithium dicyclohexylamide, 

with chlorotrimethylsilane gives 1-substituted allylsilanes, for example, allylsilanes 

28 (Scheme 14). [79] The products are uncontaminated with their 3-halogen-substituted 

isomers. This procedure seems to offer the onlyavailable route, at present, to 1-halogen-substituted 

allylsilanes. Incidentally, lithium dicyclohexylamide as the base is here a 

better choice than lithium diisopropylamide. 

Scheme 14 Synthesis of 1-Halogen-Substituted Allylsilanes [79] 

R 1 X 

TMSCl, Cy 2NLi, THF 

+ PhMe2Si MgCl 

Cl 

Br 

(R,S)-PPFA = 

+ Me 3Si MgBr 

Fe 

Ph 

PPh 2 

NMe2 

NiCl2(dppp) 97% 

PdCl2{(R,S)-PPFA} (cat.) 

Et2O, −78 to 30 oC, 4 d 

79% 

SiMe2Ph 31 

SiMe3 Ph 

32 66% ee 

Vinyl halides containing one or more hydroxy groups are also amenable to this protocol; 

however, in situ deprotonation of the alcoholic groups [84,85] is a necessaryprerequisite for 

success, as in, for example, the one-pot preparation [84] of the valuable conjunctive reagent 

34 [1,69] (Scheme 16). 

Scheme 16 One-Pot Preparation of [2-(Acetoxymethyl)allyl]trimethylsilane [84] 

Cl 

OH 

33 



1. BuLi, THF, 0 oC, 10 min 

2. Me3SiCH2MgCl, NiCl2(dppp) (cat.), reflux 

3. AcCl, py, 0 oC, 10 min 

50% 

(R)-Trimethyl(1-phenylallyl)silane (32); Typical Procedure: [83] 

To a mixture of vinyl bromide (4.3 g, 40 mmol) and the catalyst [PdCl 2{(R,S)-PPFA}] {(R,S)- 

PPFA, (R)-N,N-dimethyl-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine} (0.2 mmol) 

was added a 0.6±1 M soln of [1-(trimethylsilyl)benzyl]magnesium bromide in Et 2O 

(80 mmol) at ±788C. The mixture was stirred at 308C for 4 d, and then hydrolyzed with 

3 M aq HCl at 08C. The organic layer was separated, and the aqueous layer was extracted 

with Et 2O. The combined organic extracts were washed with sat. aq NaHCO 3 and H 2O, and 

dried (MgSO 4). The solvent was removed under reduced pressure and the residue was distilled; 

this gave chiral allylsilane 32 (66% ee); yield: 6.09 g (79%); bp 558C/0.4 Torr. (Lower 

reaction temperatures give higher enantioselectivities, but lower yields; in the above 

case, stirring at 08C for 4 d gave the product in 42% yield but with 95% ee.) 

[2-(Acetoxymethyl)allyl]trimethylsilane (34): [84] 

Into a flame-dried 25-mL flask containing a stirring bar was added Mg turnings (113 mg, 

4.66 mmol) followed bydryTHF (15 mL). After the Mg surface had been activated with 

three drops of 1,2-dibromoethane, Me 3SiCH 2Cl (500 mg, 4.08 mmol) was added. This mixture 

was refluxed for 1 h and then cooled to rt after formation of Me 3SiCH 2MgCl. In a separate 

dried flask, allyl alcohol 33 (269 mg, 2.91 mmol) was dissolved in dryTHF (20 mL), 

and 1.52 M BuLi in hexane (1.91 mL, 2.91 mmol) was added at 08C. After stirring for 

10 min, this mixture was transferred bycannula into the flask containing the Grignard 

reagent; addition of [NiCl 2(dppp)] (95 mg, 0.07 mmol) followed. The mixture was then refluxed 

and the progress was monitored byTLC. When the coupling was adjudged complete 

byTLC analysis, the soln was cooled to 08C and pyridine (691 mg, 8.73 mmol) was 

added, followed byAcCl (681 mg, 8.73 mmol). The acetylation was monitored carefully 

byTLC, and, after 10 min, the mixture was diluted with Et 2O, washed successivelywith 

OAc 

34 

SiMe3 



10% aq HCl and sat. aq NaHCO 3, and dried (MgSO 4). After the solvent had been removed in 

vacuo, the residue was flash chromatographed (pentane); yield: 271 mg (50%). 

4.4.40.7.2 Variation 2: 

From Enol Phosphates with [(Trialkylsilyl)methyl]magnesium Halides 

Nickel acetylacetonate catalyzed cross coupling of enol phosphates with [(trialkylsilyl)methyl]magnesium 

halides offers a reliable route to allylsilanes, for example, silane 

35 (Scheme 17). [86] A varietyof other transition-metal catalysts such as nickel(II) bromide 

and tetrakis(triphenylphosphine)palladium(0) have been found to be equally useful for 

such coupling reactions. The required enol phosphates have been prepared bythe addition 

of diethyl chlorophosphate to the lithium enolate, generated from a ketone and lithium 

diisopropylamide under kinetically controlled conditions. [86] Of note is the compatibilityof 

this protocol with reactive functional groups, [87,88] as shown by, for example, the 

preparation of silane 36 (Scheme 17). [87] 

Scheme 17 Allylsilanes from Enol Phosphates [86,87] 

OPO(OEt) 2 

CO2Me 

OPO(OEt)2 



Me3SiCH2MgCl Ni(acac) 2 (cat.), 15 h 

81% 

Me3SiCH2MgCl Ni(acac) 2 (cat.) 

35 

SiMe 3 

36 

SiMe3 

CO2Me 

Conversion of Enol Phosphates into Allylsilanes; General Procedure: [86] 

Into a 50-mL flask, equipped with a stirring bar, were successivelyadded the catalyst (0.1± 

0.15 mmol), a soln of Me 3SiCH 2MgCl (5±9 mmol) in Et 2O, and the enol phosphate 

(3 mmol). The flask was sealed with a serum cap. The mixture was stirred at rt for 15 h 

and hydrolyzed with dil HCl (15 mL) under cooling with an ice bath. The organic layer 

was separated and the aqueous layer was extracted with Et 2O (2 ” 220 mL). The combined 

organic layers were washed with sat. aq NaHCO 3 (30 mL) and H 2O, and dried (Na 2SO 4). The 

solvent was removed under reduced pressure and the allylsilane was isolated by distillation 

in vacuo and/or column chromatography(silica gel, hexane). 

(Cyclohex-1-enylmethyl)trimethylsilane (35); yield: 81%; bp 708C/5 Torr. 

4.4.40.7.3 Variation 3: 

From Vinyl Trifluoromethanesulfonates with 

Tris[(trimethylsilyl)methyl]aluminum 

Allylsilanes, for example, 38 and 39 (Scheme 18), are available bypalladium(0)-catalyzed 

cross coupling of vinyl trifluoromethanesulfonates (triflates) with tris[(trimethylsilyl)methyl]aluminum, 

generated in situ from 3 equivalents of [(trimethylsilyl)methyl]lithium 

and 1 equivalent of aluminum trichloride. [89] Besides the high stereospecificityof 

this procedure, its compatibilitywith the presence of a host of reactive functional groups 

in substrates is noteworthy. 


Scheme 18 Allylsilanes from Vinyl Trifluoromethanesulfonates [89] 

EtO2C 

37 

OTf 

OTf 

Al(CH2SiMe3)3 

Pd(PPh3)4 (cat.), 23 oC, 2 h 

81% 

Al(CH2SiMe3)3 

Pd(PPh3)4 (cat.) 

EtO2C EtO 2C 

39 

EtO2C 

{[4-(Ethoxycarbonyl)cyclohex-1-enyl]methyl}trimethylsilane (38); Typical Procedure: [89] 

To a magneticallystirred suspension of AlCl 3 (1.13 g, 8.5 mmol) in dry1,2-dichloroethane 

(50 mL) under argon was added, over 10 min, 1 M Me 3SiCH 2Li in pentane (26 mL, 

26 mmol). The resulting mixture was stirred at rt for 30 min, and then treated rapidly, by 

cannula transfer, with a soln of trifluoromethanesulfonate 37 and the catalyst Pd(PPh 3) 4, 

which was prepared in a separate flask as follows: A soln of Pd(OAc) 2 (130 mg, 0.58 mmol) 

and Ph 3P (610 mg, 2.33 mmol) in drybenzene (25 mL) was treated under argon with 2.5 M 

BuLi in hexane (0.5 mL, 1.25 mmol). Trifluoromethanesulfonate 37 (1.8 g, 6 mmol) was 

added 5 min later, either as a neat liquid or dissolved in drybenzene (10 mL). This soln 

was immediatelytransferred bycannula as described above, and the resulting mixture 

was stirred for 2 h at 238C. The workup consisted of dilution with CH 2Cl 2 and washing 

with 0.2 M aq HCl, H 2O, and brine, followed bydrying (MgSO 4). Purification byflash chromatography(silica 

gel, CH 2Cl 2/hexane) gave the pure product as a colorless liquid; yield: 

1.17 g (81%). 

SiMe3 

4.4.40.8 Method 8: 

From á-Silyl Aldehydes and Alkylidinetriphenylphosphoranes 

by a Wittig Reaction 

Optically active 1-substituted or 1,3-disubstituted prop-2-enylsilanes, for example, allylsilanes 

(S)-40 (Scheme 19), can be synthesized from the homochiral á-silyl aldehydes by 

Wittig alkenation with alkylidenetriphenylphosphoranes. [94] Enantiomericallyenriched 

á-silyl aldehydes are available from simple aldehydes and silylating agents employing the 

(S)-(±)- or (R)-(+)-1-amino-2-(methoxymethyl)pyrrolidine (SAMP or RAMP) hydrazone method. 

[95] For generation of alkylidenetriphenylphosphoranes, use of butyllithium is recommended, 

since sodium amide leads to substantial racemization of silyl aldehydes. 

Scheme 19 Homochiral Allylsilanes from a Chiral á-Silyl Aldehyde [94] 

O 

H 

SiMe2Bu t 

( ) 5 



R1CH2PPh3 X − 

+ 

BuLi, THF 

R1 = H 80% 

R1 = Me 80%; (E/Z) 97:3 

R 1 

38 

H ( ) 5 

SiMe2Bu t 

(S)-40 R1 = H > 98% ee 

R1 = Me 98% ee 

Enantiomerically Enriched Allylsilanes from Chiral á-Silyl Aldehydes; 

General Procedure: [94] 

At ±78 8C, under argon, 1.6 M BuLi in hexane (6.2 mL, 10 mmol) was added over ca. 20 min 

to a well-stirred suspension of the alkyltriphenylphosphonium halide (16 mmol) in dry 

THF (50 mL). The mixture was allowed to warm to rt (ca. 208C) over 2 h. In a separate flask, 

the chiral á-silyl aldehyde (10 mmol) was dissolved, with stirring, in dry THF (20 mL) and 

was cooled to ±788C. The pregenerated ylide was then added slowly to the aldehyde 


− 

>− 

SiMe 3 


through a double-ended needle. The color of the ylide disappeared instantly. The mixture 

was stirred for another 1±1.5 h, poured onto crushed ice, and extracted with pentane 

(4 ” 25 mL). The organic phase was washed with H 2O (25 mL) and brine (25 mL), dried 

(MgSO 4), and filtered, and the solvent was removed in vacuo (ca. 208C, 15 Torr). The residue 

was purified byflash chromatography(silica gel, Et 2O/pentane 1:49) to give the pure 

allylsilane. [In the case of relatively unstable and highly volatile á-silyl aldehydes, the corresponding 

á-silyl SAMP (or RAMP) hydrazone was cleaved by ozonolysis in dry pentane at 

±78 8C and the mixture was used directlyfor the Wittig alkenation after the solvent was 

removed under reduced pressure (15 Torr) at ca. 0 8C.] 

(S)-tert-Butyl(1-hexylallyl)dimethylsilane [(S)-40, R 1 = H]; yield: 80%. 

4.4.40.9 Method 9: 

From Carbonyl Compounds and Trialkyl[2-(trimethylsilyl)ethylidene]phosphoranes 

by a Wittig Reaction 

Terminally substituted allylsilanes have been prepared by Wittig alkenation of carbonyl 

compounds with triphenyl[2-(trimethylsilyl)ethylidene]phosphorane (41, Ar 1 = Ph), generated 

bydeprotonation of its phosphonium salt (Scheme 20). [96±98] The limitations of the 

method are the lack of E/Z selectivity, the difficulty in extending this protocol to the preparation 

of allylsilanes with a substituent on C1, as there is no easy way to make the requisite 

ylides, and the formation of byproduct 42 bysilyl-group rearrangement when the 

reaction is run under more or less diluted conditions. [1] Replacement of alkylidenephosphorane 

41 (Ar 1 = Ph) bythe stericallymore congested 41 (Ar 1 = 2-Tol) in these reactions 

improves stereoselectivityin favor of the Z-isomer, as well as yields, by suppressing the 

formation of ether 42. [99] If ylide 41 (Ar 1 = Ph) is generated with sodium silazide, Z selectivityis 

also improved, albeit with reduced yields. [100] 

Scheme 20 Allylsilanes by a Wittig Reaction [96±99] 

R 1 

H 

O 

+ 

SiMe3 

Ar1 1 

3P 2 

41 Ar1 = Ph, 2-Tol 

R 1 SiMe 3 

H 

+ 

R 1 

OSiMe3 

Two variations of this method have been reported, particularlywith ylide 41 (Ar 1 = Ph) as 

reagent; in one reaction the ylide is generated from a preformed phosphonium salt, while 

in the other the phosphonium salt is generated in situ. It works particularlywell for aldehydes 

and some reactive ketones, such as cyclohexanone and acetophenone, but gives 

poor yields with cyclopentanone and when there is alkyl substitution on C2 of the ylide. [1] 

4.4.40.9.1 Variation 1: 

Via a Preformed â-Silylated Phosphonium Salt 

Allylsilanes are accessible by alkenation of carbonyl compounds with triphenyl(â-silylalkylidene)phosphorane 

41 (Ar 1 = Ph), prepared in two steps: reaction of methylidenetriphenylphosphorane 

with (iodomethyl)trimethylsilane, followed by deprotonation of the 

resulting crystalline salt 43. This method is illustrated in the preparation of 44 (Scheme 

21). [96,97] 

Scheme 21 Allylsilanes by Wittig Reaction with a Preformed â-Silylated Phosphonium 

Salt [96,97] 

+ 

Ph3P 43 

SiMe 3 

I − 



PhLi 

Ph 3P 

SiMe 3 

41 Ar 1 = Ph 44 (E/Z) 1.7:1 

42 

Me(CH2)5CHO 

( ) 

71% 5 


SiMe 3

Trimethyl(non-2-enyl)silane (44); Typical Procedure: [97] 

A 200-mL, three-necked, round-bottomed flask equipped with a mechanical stirrer and a 

condenser fitted with an argon inlet tube was flame-dried, flushed with argon, and 

charged with phosphonium iodide 43 (9.81 g, 20 mmol) and THF (80 mL). The slurrywas 

cooled to 08C, and subsequently1 M PhLi in Et 2O (21.2 mL, 21.2 mmol) was added dropwise 

under continuous stirring. The mixture immediatelyturned red, and after stirring 

at rt for 1 h, it formed a homogeneous red soln. Heptanal (3 mL, 22 mmol) was added dropwise 

and the mixture was refluxed for 15 h. During this time the red ylide color disappeared. 

In vacuo trap-to-trap distillation of volatiles into a receiver cooled to ±788C was 

followed byconcentration of the distillate. Distillation of the residue gave the product. 

GC analysis of an aliquot of the trap-to-trap distillate showed that the product had 

formed; yield: 2.81 g (71%). 

4.4.40.9.2 Variation 2: 

Via an In Situ Generated â-Silylated Phosphonium Salt 

Terminal allylsilanes have also been prepared from in situ generated ylide 41 (Ar 1 = Ph). 

Thus, sequential treatment of methyltriphenylphosphonium bromide (45) with butyllithium 

and (iodomethyl)trimethylsilane, followed by a second equivalent of butyllithium, 

generates 41 (Ar 1 = Ph), which on treatment with an aldehyde or ketone gives the allylsilane, 

for example, 46 (Scheme 22). [98] 

Scheme 22 Allylsilanes by Wittig Reaction with an In Situ Generated â-Silylated 

Phosphonium Salt [98] 

Ph3PMe Br − 

+ 

45 

1. BuLi, THF 

2. Me3SiCH2I 3. BuLi 



Ph 3P 

SiMe 3 

41 Ar 1 = Ph 46 86% 

(2-Cyclohexylideneethyl)trimethylsilane (46); Typical Procedure: [98] 

Over 0.5 h, 1.66 M BuLi in hexane (15 mL, 25 mmol) was added dropwise to a stirred suspension 

of phosphonium salt 45 (8.03 g, 22.5 mmol) in dryTHF (40 mL) at 08C under N 2. 

The mixture was warmed to rt and stirred for 1 h, recooled to 0 8C, and Me 3SiCH 2I (4.82 g, 

22.5 mmol) was added over 10 min. The mixture was again allowed to come slowlyto rt, 

to precipitate the new phosphonium salt. After 1 h, the mixture was treated at ±788C with 

a second equiv of 1.66 M BuLi in hexane (15 mL, 25 mmol). The mixture was allowed to 

warm slowlyto rt, and stirred for a further 1.5 h to give a dark-red soln of ylide 41 

(Ar 1 = Ph). Cyclohexanone (1.96 g, 20 mmol) in dry THF (10 mL) was then added dropwise 

over 15 min to the ylide soln at ±788C under N 2. After 0.5 h, the mixture was allowed to 

warm slowlyto rt, was stirred under N 2 for a further 16 h, was quenched bybeing poured 

into sat. aq NH 4Cl (100 mL), and was extracted with Et 2O (3 ” 300 mL). The combined organic 

extracts were dried (MgSO 4) and concentrated in vacuo. The allylsilane was isolated 

(>98% pure, byGC) either bychromatography(silica gel, CCl 4) or bydistillation; yield: 

3.13 g (86%). 

4.4.40.10 Method 10: 

From Carbonyl Compounds and Ethyl 2-(Diethoxyphosphoryl)- 

3-(trimethylsilyl)propanoate by Horner±Wadsworth±Emmons Reaction 

2-(Alkoxycarbonyl)allylsilanes are available from aldehydes by the Horner±Wadsworth± 

Emmons reaction with ethyl 2-(diethoxyphosphoryl)-3-(trimethylsilyl)propanoate (48), 

generated in situ by deprotonation of ethyl (diethoxyphosphoryl)acetate (47) with 1 


O 

SiMe 3 


equivalent of sodium hydride, followed by alkylation with (iodomethyl)trimethylsilane. 

This procedure has been used for the preparation of 49 [R 1 = Me, 2-(CH 2) 5OTHP] (Scheme 

23). [101±103] Stereoselectivityof this one-pot process is low. In addition, poor yields have 

been obtained with aldehydes containing a benzyloxy substituent at the 4-position. [104] 

The alkenation reaction can also be carried out with preformed phosphonate 48; this 

leads to improved Z selectivity. [105,106] 

Scheme 23 Synthesis of 2-(Alkoxycarbonyl)allylsilanes by the Horner±Wadsworth±Emmons 

Reaction [101±103] 

EtO 

O 

P CO2Et EtO 



1. NaH, DME 

2. Me3SiCH2I EtO 

O 

P CO2Et EtO 

47 48 

1. NaH 

2. R1CHO SiMe3 

R 1 

CO2Et 

SiMe 3 

49 R 1 = Me 49%; (E/Z) 1:4 

R 1 = 79%; (E/Z) 1:2 

Ethyl 8-(Tetrahydropyran-2-yloxy)-2-[(trimethylsilyl)methyl]oct-2-enoate 

[49,R 1 = 2-(CH 2) 5OTHP]; Typical Procedure: [103] 

After 60% NaH in mineral oil (248 mg, 6.20 mmol) had been placed in a 50-mL two-necked 

flask under argon, the dispersion was washed with dryhexane (3 ”) to remove the mineral 

oil. The flask was cooled in an ice bath, and dryDME (5 mL), followed bya soln of phosphonate 

47 (1.12 mL, 5.65 mmol) in DME (3 mL) were added dropwise. After the mixture 

had stirred for 30 min at rt, a soln of Me 3SiCH 2I (1.0 mL, 6.7 mmol) in DME (2 mL) was 

added, and the mixture was warmed to 708C for 4 h. It was cooled to 08C again, and a second 

portion of NaH (203 mg, 5.08 mmol) was added. After the mixture had stirred at rt for 

1.5 h, a soln of 6-(tetrahydropyran-2-yloxy)hexanal (802 mg, 3.75 mmol) in DME (5 mL) was 

added at 08C, and the mixture was stirred at rt overnight. Aq NH 4Cl was added to quench 

the mixture, which was extracted with Et 2O. The Et 2O soln was dried (MgSO 4) and concentrated, 

and the crude product was chromatographed (silica gel, hexane/Et 2O 19:1), to afford 

the product as an oil [(E/Z) 1:2]; yield: 1.09 g (79%). 

4.4.40.11 Method 11: 

From Carbonyl Compounds and â-Silyl Thioacetals by 

Titanium(II)-Promoted Reductive Alkenation 

Allylsilanes are available from carbonyl compounds by titanium(II)-promoted reductive 

alkenation of â-silylthioacetals. In this protocol, the low-valency titanium species 50 

(Scheme 24), generated in situ from dichlorobis(cyclopentadienyl)titanium(IV) and magnesium 

in the presence of triethyl phosphite, reduces the â-silylthioacetal, and the follow-up 

treatment with an aldehyde or a ketone produces the allylsilane, for example, 52 

(Scheme 24). [107] In spite of moderate stereoselectivity, this method has an advantage over 

the other carbonyl alkenation reaction (Section 4.4.40.9), in that ã-heteroatom-substituted 

allylsilanes can be prepared from carboxylic acid derivatives, as in the preparation of 

allylsilane 53. The mechanism of this reaction probablyinvolves a titanium±alkylidene 

( ) 

5 O 


O

complex which reacts with the carbonyl compound via an oxatitanacyclobutane intermediate. 

[108] 

Scheme 24 Alkenation of Carbonyl Compounds by â-Silyl Thioacetals [107] 

TiCp2Cl2 

[TiCp2{P(OEt)3}2] 

50 



Mg, P(OEt) 3 

THF, 4-Å molecular sieves 

rt 

1. PhMe 2SiCH 2CH(SPh) 2 51 

2. Bu t 

64% 

O 

1. Me3SiCH2CH(SPh)2 

2. BzOMe 

81% 

Bu t 

MeO 

52 

SiMe 3 

Ph 

53 (E/Z) 18:82 

SiMe 2Ph 

[2-(4-tert-Butylcyclohexylidene)ethyl]dimethylphenylsilane (52); Typical Procedure: [107] 

THF (4 mL) and P(OEt) 3 (0.62 mL, 3.6 mmol) were added to a stirred flask charged with finelypowdered 

4-Š molecular sieves (180 mg), Mg turnings (53 mg, 2.2 mmol), and [TiCp 2Cl 2] 

(448 mg, 1.8 mmol), at rt and under argon. After 3 h, silane 51 (228 mg, 0.6 mmol) in THF 

(1 mL) was added to the mixture, which was stirred for a further 10 min. Then 4-tert-butylcyclohexanone 

(77 mg, 0.5 mmol) in THF (1.5 mL) was added dropwise over 15 min. After 

the mixture had stirred for 2 h, the reaction was quenched byaddition of 1 M NaOH, and 

the resulting insoluble materials were removed byfiltration through Celite. The filtrate 

was extracted with Et 2O, and the extract was dried (Na 2SO 4). After the solvent had been 

removed, the residue was purified bypreparative TLC (hexane); yield: 97 mg (64%). 

4.4.40.12 Method 12: 

From Carbonyl Compounds and Trimethyl[2-(phenylsulfonyl)ethyl]silane 

by the Julia Reaction 

Allylsilanes are available from aldehydes and ketones by reaction with a metalated sulfone, 

generated from trimethyl[2-(phenylsulfonyl)ethyl]silane (54) and butyllithium, followed 

bymesylation of the resultant alcohol, and reductive elimination of the crude 

methanesulfonate with 6% sodium amalgam. This method is used for the preparation of 

allylsilanes 55 (Scheme 25). [109,110] Sulfone 54 is available from trimethyl(vinyl)silane by 

radical-catalyzed addition of benzenethiol, followed by oxidation. The formation of 55 

[R 1 ,R 2 = (CH 2) 3;R 1 =R 2 = Ph] indicates that the presence of strain or steric hindrance in carbonyl 

groups does not seriously impede reaction of the metalated sulfone. [110] Moreover, 

the method works for the preparation of (2-cyclopentylideneethyl)trimethylsilane [55, 

R 1 ,R 2 = (CH 2) 4], where Wittig alkenation fails, but, like the Wittig reaction, lacks stereoselectivity, 

as is the case for the preparation of silane 55 (R 1 =H; R 2 = Ph) (see also Section 

4.4.40.9). It has been suggested that 1,2-dimethoxyethane may be the solvent of choice 

for addition of metalated sulfone derived from 54 to enolizable aldehydes. [111] 



Scheme 25 Allylsilanes from Trimethyl[2-(phenylsulfonyl)ethyl]silane [109,110] 

SiMe 3 

1. PhSH, AIBN 

2. H2O2 O O 

S 

Ph 

54 

SiMe 3 

1. BuLi 

2. R1R2CO 3. MsCl 

4. 6% Na/Hg 

R1 ,R2 = (CH2) 3 95% 

R1 ,R2 = (CH2) 4 94% 

R1 = R2 = Ph 95% 

R1 = H; R2 = Ph 92% 

(2-Cyclopentylideneethyl)trimethylsilane [55,R 1 ,R 2 = (CH 2) 4]; Typical Procedure: [109] 

1.6 M BuLi in hexane (40 mL, 64 mmol) was syringed slowly into a suspension of sulfone 

54 (15 g, 62 mmol) in anhyd Et 2O (70 mL) at ±708C. The white suspension changed immediately 

to a pale yellow soln. After the mixture had stirred for 25 min, cyclopentanone 

(5.4 g, 62 mmol) was added. The soln was warmed to rt over 20 min, cooled to ±108C, and 

MsCl (7.1 g, 62 mmol) in anhyd Et 2O (5 mL) was introduced. A white precipitate of LiCl 

formed instantly. The suspension was refluxed for 25 min, cooled, diluted with Et 2O 

(100 mL), washed with aq NaCl, dried (MgSO 4), filtered, and concentrated. The colorless 

residue was dissolved without further purification in a mixture of MeOH (50 mL) and 

Na 2HPO 4 (35.2 g, 0.25 mol). After the resulting suspension had been cooled to ca. 0 8C, 6% 

Na/Hg amalgam (75 g) was added in small portions. The reductive elimination was completed 

in 1 h. The suspension was diluted with Et 2O, decanted, and the solvent was removed 

in vacuo. The residue was diluted with petroleum ether (bp 35±60 8C, 100 mL), 

washed with H 2O, dried (MgSO 4), and passed through a short column (silica gel). Removal 

of the solvents under reduced pressure gave the product; yield: 9.8 g (94%). 

4.4.40.13 Method 13: 

Formation of Exocyclic Allylsilanes by the Ramberg±Bäcklund Reaction 

Six-membered exocyclic allylsilanes with a variety of substituents â to silicon have been 

prepared bythe Ramberg±Bäcklund alkenation reaction of á-sulfonyl sulfones. [112] For example, 

treatment of bis-sulfone 57 with butyllithium at ±788C, followed bywarming to 

room temperature, yields allylsilane 58 (R 1 = H) (Scheme 26). [112] If the lithiated sulfone 

from 57 is alkylated, and a second equivalent of butyllithium is added, â-substituted allylsilanes, 

for example, 58 (R 1 = Me, Bn), maybe synthesized bythis protocol. Bis-sulfone 57 

is available from cyclohexyl phenyl sulfone (56) bylithiation followed bysulfenylation 

and oxidation with 3-chloroperoxybenzoic acid. 

Scheme 26 Preparation of Exocyclic Allylsilanes by the Ramberg±Bäcklund Reaction [112] 

O 

O 

Ph 

S H 

56 



1. BuLi 

2. Me3Si(CH2)2STs 3. MCPBA 

O O O O 

Ph 

S S 

57 

SiMe3 

1. BuLi, −78 oC 2. R1X, −78 to −20 oC 3. BuLi, −78 to 25 oC R 2 

R 1 

R 1 

R1 = H 80% (step 1 only) 

R1 = Me 69% 

R1 = Bn 80% 58 


55 

SiMe 3 

SiMe 3

(2-Cyclohexylidenepropyl)trimethylsilane (58, R 1 = Me); Typical Procedure: [113] 

To a soln of bis-sulfone 57 (320 mg, 0.832 mmol) in THF (5 mL) at ±788C was added BuLi 

(1 mmol), and the mixture was stirred at ±788C for 30 min. HMPA (0.5 mL) was added, 

and the mixture was stirred for 5 min. Then MeI (177 mg, 1.248 mmol) was added, the 

mixture was warmed to ±208C, stirred at this temperature for 1 h, and then cooled to 

±78 8C. BuLi (1.248 mmol) was added and the mixture was allowed to warm to 0 8C over 

30 min. The mixture was quenched with sat. aq NH 4Cl and diluted with Et 2O (50 mL). The 

Et 2O layer was washed with sat. aq NaHCO 3 and brine and dried (MgSO 4); then the solvent 

was removed in vacuo. The residue was purified bychromatography(Florisil, hexane); 

yield: 112 mg (69%). 

4.4.40.14 Method 14: 

From 1,3-Dienes by Hydrosilylation 

Z-Allylsilanes are available by transition-metal-catalyzed 1,4-hydrosilylation of conjugated 

acyclic dienes, [114±116] as exemplified bythe preparation of (Z)-59 [116] (Scheme 27). In addition, 

regioselective synthesis of (Z-2-ethylidenecycloalkyl)silanes, for example, 60, is 

possible by hydrosilylation of 1-vinylcycloalkenes with dichloromethylsilane (Scheme 

27). [117] The use of a chiral palladium catalyst allows the synthesis of enantiomerically enriched 

acyclic allylsilanes. [118,119] For example, enantiomericallyenriched 1,3-unsymmetricallysubstituted 

allylsilanes, such as 61, have been prepared by catalytic asymmetric hydrosilylation 

of (E)-1-phenylbuta-1,3-diene with fluorodiphenylsilane in the presence of a 

palladium catalyst, generated in situ from the (ç 3 -allyl)chloropalladium(II) dimer and (R)- 

2-diphenylphosphino-2¢-hydroxy-1,1¢-binaphthyl [(R)-MOP], followed bytreatment with 

methyllithium (Scheme 27). [118] The regio- and enantioselectivities in this case have been 

found to be stronglyaffected bythe structure of the hydrosilane and the phosphine ligand. 

[118] For example, reversal of enantioselectivityoccurs in the case of 61 when the 

tert-butyldimethylsilyl ether of (R)-2-diphenylphosphino-2¢-hydroxy-1,1¢-binaphthyl is 

used. [118] For asymmetric hydrosilylation of cyclic 1,3-dienes, (R)-3-diphenylphosphino-3¢methoxy-4,4¢-biphenanthryl 

[(R)-MOP-phen] is a more efficient chiral ligand than the 

related (R)-MOP ligands for high enantioselectivity, as shown by the preparation of chiral 

silane 62. [120] 

Scheme 27 Allylsilanes by Hydrosilylation of 1,3-Dienes [116±118,120] 

( ) n 

+ HSiCl 3 

Ph 

+ HSiCl3 

+ HSiMeCl 2 

+ HSiPh2F 



Pd(PPh3) 4, −78 oC 84% 

PdCl2(PPh3) 2 

80 oC, 3 h 

84% 

74% 

SiCl3 (Z)-59 (E/Z) 1:99 

SiMeCl2 60 (E/Z)

HO 

PPh 2 

MeO 

b(R)-MOP (R)-MOP-phen 

[(Z)-But-2-enyl]trichlorosilane [(Z)-59]: [116] 

HSiCl 3 (56 g, 0.413 mol) and Pd(PPh 3) 4 (0.93 g, 0.8 mmol) were placed in an argon-purged 

autoclave (100 mL). Introduction of buta-1,3-diene (34 mL, 0.40 mol) into the vessel at 

±78 8C, stirring for 6 h, and the usual workup gave the product; yield: 63.67 g (84%). 

Methyldiphenyl[(S,Z)-1-phenylbut-2-enyl]silane (61): [118,121] 

A 20-mL sealed tube containing a magnetic stirring bar was charged with (R)-MOP (17 mg, 

0.038 mmol), [Pd 2(ç 3 -allyl) 2Cl 2] (6.4 mg, 0.035 mmol of Pd), 1-phenylbuta-1,3-diene (0.48 g, 

3.6 mmol), and HSiPh 2F (0.74 g, 3.7 mmol) under argon, and the mixture was stirred at rt 

(ca 208C) for 12 h. Excess MeLi in Et 2O was added to convert the Si-F group into an Si-Me 

group. Quenching with sat. aq NH 4Cl, extraction, drying (Na 2SO 4), and concentration, followed 

bypreparative TLC (silica gel, hexane) gave the product [66% ee, byHPLC (Daicel 

Chiralcel-OD, hexane)]; yield: 0.87 g (74%); [á] D ±6.35 (c 1.51, CHCl 3). 

(R)-Trichloro(cyclopent-2-enyl)silane (62, n = 1); Typical Procedure: [120,122] 

Under dryN 2, HSiCl 3 (0.3 mL, 3.0 mmol) was added to a mixture of [Pd 2(ç 3 -allyl) 2Cl 2] 

(0.52 mg, 0.0028 mmol Pd), (R)-MOP-phen (2.58 mg, 0.00454 mmol), and cyclopenta-1,3-diene 

(0.158 g, 2.4 mmol) at 08C. The mixture was stirred at 208C for 5 d. The completion of 

the reaction was confirmed byGC analysis. In vacuo bulb-to-bulb distillation of the mixture 

gave the product (80% ee); yield: 0.48 g (99%); bp 105 8C/20 Torr. 

4.4.40.15 Method 15: 

From 1,3-Dienes by Carbosilylation 

Decarbonylative coupling of an acid chloride, organodisilane, and 1,3-diene in the presence 

of bis(dibenzylideneacetone)palladium(0) provides E-allylsilanes by 1,4-carbosilylation 

(Scheme 28). The presence of a varietyof functional groups in the acid chloride component 

is compatible with this procedure, shown in the preparation of 63 (R 1 = Ph, 

4-O 2NC 6H 4, 4-AcC 6H 4) (Scheme 28). Tri- and tetrasubstituted allylsilanes are also available 

by this method, if 2-methyl or 2,3-dimethylbutadiene is used as the diene component. 

[123,124] 

PPh 2 

Scheme 28 Allylsilanes by Decarbonylative Coupling of an Acid Chloride, Disilane, 

and 1,3-Diene [123,124] 

R 1 COCl + 

Me3Si SiMe 3 + 



Pd(dba) 2 

80 o C, 4 h 

R1 = Ph 86% 

R1 = 4-O2NC6H4 51% 

R1 = 4-AcC6H4 92% 

[(E)-4-Phenylbut-2-enyl]trimethylsilane (63,R 1 = Ph): [124] 

1.6 M Buta-1,3-diene in toluene (0.94 mL, 1.5 mmol), Pd(dba) 2 (14 mg, 0.025 mmol), BzCl 

(70 mg, 0.50 mmol), Me 3SiSiMe 3 (73 mg, 0.50 mmol), and toluene (2 mL), together with a 

magnetic stirring bar, were placed under argon in a 30-mL stainless-steel autoclave containing 

an inserted glass liner. An air purge was ensured bythree pressurization 


R 1 

63 

SiMe 3

(2 ” 10 3 kPa)±depressurization sequences with argon. The autoclave was heated to 808Cin 

10 min and held at this temperature for 4 h. The reaction was terminated byrapid cooling, 

and the autoclave was discharged. The resulting mixture was passed through a short 

Florisil column. The product was isolated byMPLC (silica gel, hexane) followed byKugelrohr 

distillation (bath temperature 80 8C/0.3 Torr); yield: 88 mg (86%). 

4.4.40.16 Method 16: 

From Allyl Halides by Copper(I)-Catalyzed Silylation with Trichlorosilane 

Allyltrichlorosilanes are available from allylic halides and trichlorosilane in the presence 

of an equimolar amount of triethylamine and a catalytic amount of a metal salt such as 

cuprous chloride, as shown bythe preparation of (E)-59 (Scheme 29). [116,125] The products 

of this reaction are readily convertible to the corresponding trimethylsilyl- and related derivatives, 

for example, allylsilane 64 (Scheme 29), whose synthesis proved troublesome 

bya Horner±Wadsworth±Emmons reaction [104] (Section 4.4.40.10). 2-Bromoallyl- and 

(3-bromoallyl)trimethylsilanes, available by this procedure, are valuable reagents, as 

theycan provide a varietyof functionalized allylsilanes via the 1- and 2-metallo derivatives. 

[126±132] Incidentally, a copper(I) salt is not essential in this reaction if an amine carrying 

a long alkyl chain, such as tributylamine, is used. [133] 

Scheme 29 From Allyl Halides by Copper(I)-Catalyzed Silylation [104,116,125] 

BzO 

Cl 

HSiCl3, Et3N 

CuCl (cat.) 

76% 

Br 



CO2Me 

SiCl 3 

(E)-59 (E/Z) 99:1 

1. HSiCl3, Et3N, CuI (cat.) 

2. MeLi (excess) 

[(E)-But-2-enyl]trichlorosilane [(E)-59]; Typical Procedure: [116,125] 

A mixture of (E)-but-2-enyl chloride (5.44 g, 60.0 mmol), HSiCl 3 (11.68 g, 86.2 mmol), and 

Et 2O (10 mL) was added to an Et 2O suspension (30 mL) of CuCl (200 mg, 2.0 mmol) and 

Et 3N (7.20 g, 71.1 mmol) at rt. After being stirred for 1.5 h, the mixture was filtered. Distillation 

of the filtrate gave 59 [(E/Z) 99:1]; yield: 8.6 g (76%); bp 142±1448C/760 Torr. 

4.4.40.17 Method 17: 

From Allenes by Palladium(0)-Catalyzed Carbosilylation 

2,3-Disubstituted and 2,3,3-trisubstituted allylsilanes have been prepared by a three-component 

coupling reaction involving a 1-substituted allene, an aryl iodide, and tributyl(trimethylsilyl)stannane 

in the presence of bis(dibenzylideneacetone)palladium(0) as catalyst, 

for example, the formation of allylsilanes 65 (Scheme 30). [134] Note that the presence 

of a varietyof electron-donating or -withdrawing functional groups on the aryl ring is 

compatible with this procedure. Other useful organic halides include 3-iodocyclopent-2en-1-one 

and ethyl (Z)-3-iodoacrylate. 


HO 

64 

SiMe 3 

OH 


Scheme 30 Allylsilanes by Palladium(0)-Catalyzed Carbosilylation of Allenes [134] 

R 1 

I 

+ Bu3Sn SiMe3 + 



R 2 

R 3 

Pd(dba)2 

toluene 

R1 = H; R2 = R3 = Me 85% 

R1 = 2-OMe; R2 = R3 = Me 83% 

R1 = 4-Ac; R2 = H; R3 = Cy 80%; (E/Z) 92:8 

Allylsilanes 65; General Procedure: [134] 

A 50-mL flask containing Pd(dba) 2 (0.0287 g, 0.05 mmol) was purged with N 2 (3 ”). Toluene 

(3 mL), the organic halide (1.00 mmol), the allene (2.00 mmol), and Bu 3SnSiMe 3 (360 mg, 

1 mmol) were then added bysyringe to the flask. The mixture was heated with stirring 

at 808C for 7 h. The soln changed color rapidlyfrom purple-red to pale yellow in the first 

few min and maintained the same color for the rest of the reaction. As the reaction approached 

completion, a black precipitate of Pd(0) appeared graduallyon the wall of the 

flask. At the end of the reaction, the soln was filtered through Celite. The filtrate was concentrated, 

and the residue was purified bycolumn chromatography(silica gel, hexane). 

Trimethyl(3-methyl-2-phenylbut-2-enyl)silane (65, R 1 =H;R 2 =R 3 = Me); yield: 85%. 

[2-(2-Methoxyphenyl)-3-methylbut-2-enyl]trimethylsilane (65, R 1 = 2-OMe; R 2 =R 3 = 

Me); yield: 83%. 

4.4.40.18 Method 18: 

From Lithium Allyl Alcoholates and Hexamethyldisilane 

A direct synthesis of terminally substituted allylsilanes from allyl alcohols involves the 

generation of lithium allyl alcoholates with methyllithium and follow-up treatment 

with hexamethyldisilane in hexamethylphosphoric triamide. For example, both allyl alcohols 

66 and 67 give mixtures of the E- and Z-allylsilanes 11, in which the E-isomer predominates 

(Scheme 31). [135] Apart from allyl alcohols, carbonyl compounds can also be 

used as precursors to lithium allyl alcoholates; the latter are generated in situ by 1,2-addition 

of vinyllithium to saturated carbonyl compounds, or by addition of alkyllithium to 

á,â-unsaturated carbonyl compounds. This one-pot reaction occurs presumably by counterattack 

of the trimethylsilyl anion, generated by the reaction of alkoxide and hexamethyldisilane, 

on the silyl ether intermediate. This method does not work for the preparation 

of cyclic allylsilanes from cyclic allyl alcohols, such as cyclohex-2-en-1-ol. 


R 2 

R 3 

65 

R 1 

SiMe3

Scheme 31 Allylsilanes from Allyl Alcoholates and Hexamethyldisilane [135] 

66 

67 

OH 

1. MeLi, Et2O 2. 

80 o Me3Si SiMe3, HMPA 

C, 24 h 

72%; (E/Z) 3:1 

OH 1. MeLi, Et2O 

2. 

80 o Me3Si SiMe3, HMPA 

C, 24 h 

75%; (E/Z) 2:1 

Allylsilanes from Allyl Alcoholates; General Procedure: [135] 

An Et 2O soln of the allyl alcohol (e.g., 66 or 67) (1.0 equiv) was treated with MeLi (1.5 

equiv) at 08C, followed byMe 3SiSiMe 3 (1.5 equiv) and HMPA (Et 2O/HMPA 1:4). After Et 2O 

was boiled off under N 2, the mixture was heated at 808C for 24 h. Aqueous workup followed 

bydistillation provided the desired allylsilane (e.g., 11). 

4.4.40.19 Method 19: 

From Allyl Esters via Allylpalladium(0) Complexes 

Palladium-catalyzed silylation of allylic esters constitutes a useful protocol for the synthesis 

of allylsilanes. Two general procedures have been reported; in one, use is made of disilanes 

to introduce the organosilicon moiety, while in the other, trialkylhalosilanes are 

used in the presence of samarium(II) iodide and hexamethylphosphoric triamide. With 

geranyl acetates or neryl acetates, the latter procedure gives terminally substituted allylsilanes 

with complete control of regio- and stereoselectivity; this is not so in the procedure 

in which disilanes are used. 

4.4.40.19.1 Variation 1: 

Using Disilanes 



Allylsilanes can be obtained by treatment of allyl trifluoroacetates with organodisilanes 

in the presence of a catalytic quantity of bis(dibenzylideneacetone)palladium(0) at room 

temperature. For example, allylsilane 68 is available in excellent yield from the corresponding 

trifluoroacetate (Scheme 32). [136] Similarly, terminal allylsilane 46 is available 

from either internal (69) or terminal (70) allylic trifluoroacetates. However, geranyl trifluoroacetate 

gives terminal allylsilanes with loss of alkene geometry. [136] 

Scheme 32 By Coupling via ç 3 -Allylpalladium(0) Complexes [136] 

11 

SiMe 3 

1. Me3Si SiMe3 

2. Pd(dba)2, THF, rt 

Ph OCOCF3 94% 

Ph SiMe3 

68 (E/Z) 99:1 



1. Me3Si SiMe3 2. Pd(dba)2 

THF, rt 

92% 

OCOCF3 69 

70 

OCOCF 3 

1. Me3Si SiMe3 2. Pd(dba)2 

THF, rt 

89% 

Allylic acetates can replace the corresponding trifluoroacetates in these reactions only 

when an added chloride salt, for example, lithium chloride, is present in the reaction medium. 

However, the reactions proceed onlyat higher temperatures and are accompanied 

byreduced yields. [136] 

Configurational inversion is normally observed with cycloalkenyl trifluoroacetates. 

For example, methyl cis-5-trifluoroacetoxycyclohex-3-ene carboxylate (71) gives trans-72 

in the tetrahydrofuran/acetonitrile mixed solvent. Note that this reaction is essentially 

solvent dependent, since use of pure tetrahydrofuran leads to a 1:1 mixture of trans- and 

cis-72 (Scheme 33). [136] 

46 

SiMe 3 

Scheme 33 An Allylsilane from an Allyltrifluoroacetate with Stereochemical 

Inversion or Randomization [136] 

CO 2Me 

71 

OCOCF3 



Pd(dba)2 (cat.) 

Me3Si SiMe3 

THF, MeCN 

89% 

Pd(dba)2 (cat.) 

Me3Si SiMe3 THF 

85% 

CO 2Me 

trans-72 

CO 2Me 

trans-72 

SiMe3 

SiMe3 

+ 

1:1 

CO 2Me 

(2-Cyclohexylideneethyl)trimethylsilane (46); Typical Procedure: [136] 

A 20-mL flask was charged with Pd(dba) 2 (17 mg, 0.030 mmol) and THF (5.5 mL) under an 

argon atmosphere. The mixture was stirred, and the palladium complex dissolved, affording 

a deep-purple soln. Then Me 3SiSiMe 3 (293 mg, 2.0 mmol) and ester 69 (222 mg, 

1.0 mmol) were added in this order. The mixture turned pale yellow, and the reaction 

was allowed to proceed at rt for 12 h. The mixture was then diluted with Et 2O (20 mL), 

washed with sat. aq NaHCO 3 (20 mL), dried (MgSO 4), and concentrated. Kugelrohr distillation 

afforded silane 46; yield: 168 mg (92%); bp 80 8C/1 Torr. 

4.4.40.19.2 Variation 2: 

Using Samarium(II) Iodide and Chlorotrimethylsilane 

An alternative procedure for the preparation of terminallysubstituted allylsilanes involves 

palladium-catalyzed reductive metalation of allylic phosphates with the samarium(II) 

iodide±hexamethylphosphoric triamide complex. Thus, the E-allylsilane (E)-74 is 

available in good yield from (E)-73 (Scheme 34). [137] In general, low temperature is recom- 

cis-72 


SiMe3

mended for the synthesis of Z-allylsilanes, for example, in the preparation of (Z)-74 [contaminated 

with 3% (E)-74] from (Z)-73 with good regioselectivity[(á/ã) 95:5]. Use of the palladium 

catalyst is not mandatory, its presence only accelerates the reaction. Of note is the 

retention of the alkene geometry for geranyl- and nerylsilanes when the reactions are run 

even at room temperature, as, for example, in the preparation of (E)-11. Allyl acetates can 

also be used in this procedure, but are associated with reduced reaction rates and 

yields. [137] 

Scheme 34 Use of Samarium(II) Iodide and Chlorotrimethylsilane [137] 

( )9 

( ) 9 

(E)-73 

OPO(OEt) 2 

OPO(OEt) 2 



TMSCl, SmI2 

Pd(PPh3) 4 (cat.) 

THF, HMPA, 25 oC, 98:2 

Trimethyl[(E)-tridec-2-enyl]silane [(E)-74]; Typical Procedure: [137] 

To a mixture of 0.1 M SmI 2 in THF (5 mL, 0.5 mmol), HMPA (0.35 mL, 2 mmol), and TMSCl 

(0.25 mL, 2 mmol) was added, successively, a soln of Pd(PPh 3) 4 (12.0 mg, 0.01 mmol, 

5 mol%) in THF (0.45 mL) and phosphate (E)-73 (66.8 mg, 0.2 mmol). After the mixture 

had stirred for 1 min at rt, silica gel (ca. 1 g) and hexane (5 mL) were added. The mixture 

was passed through a short column (silica gel, Et 2O). The eluate was concentrated in vacuo 

and purified bycolumn chromatography(silica gel, hexane) to give (E)-74 with 1% of 

its Z-isomer; yield: 45.3 mg (89%). 

4.4.40.20 Method 20: 

From Allyl Alcohols by Palladium(0)-Catalyzed Intramolecular Silylsilylation 

1,3-Unsymmetrically substituted E-allylsilanes have been prepared by palladium-catalyzed 

intramolecular silylsilylation of allyl alcohols and subsequent Peterson-type elimination 

with organolithium reagents. This protocol involving 1,3 chiralitytransfer is 

equally applicable to the synthesis of enantioenriched allylsilanes. For example, the intramolecular 

silylsilylation of (R,E)-75 (99.7% ee) promoted bya catalyst generated in situ 

from bis(acetylacetonato)palladium(II) and 1,1,3,3-tetramethylbutyl isocyanide gives a 

1:1 mixture of allylsilane (S,E)-78 (99.1% ee) and cyclic siloxane 77, presumablythrough 

the highlystereoselective formation of four-membered ring 76 followed byits thermal 

disproportionation (Scheme 35). [138,139] Subsequent treatment of the mixture with butyllithium 

yields allylsilane (S,E)-78 (99.1% ee) from 77 without contamination from its Z-isomer. 

Similarly, (R,E)-78 (95.4% ee) [138] is available from (R,Z)-75 (96.0% ee). The substrates 

for these reactions have been prepared byreactions of the corresponding alcohols with 

1-chloro-1,1,2-triphenyl-2,2-dimethyldisilane in the presence of triethylamine and a catalytic 

amount of 4-dimethylaminopyridine. 


SiMe 3 


Scheme 35 Enantioenriched E-Allylsilanes by Palladium(0)-Catalyzed Intramolecular 

Bis-silylsilylation of Allyl Alcohols [138,139] 

SiMe2Ph 

Ph2Si 

O 

( ) 

5 

(R,E)-75 99.7% ee 

SiMe2Ph Ph2Si O 

( ) 5 

(R,Z)-75 96.0% ee 

Pd(acac) 2 (cat.) 

NC 

90% 

1. Pd(acac) 2 (cat.) 

NC 

2. BuLi 

84% 

H 

O SiPh2 

H 

( ) 

5 

H 

SiMe2Ph 

76 

Ph2Si 

O 

O 

SiPh2 

H + 

( ) 

5 

H ( ) 

5 

PhMe2Si H 

77 

SiMe2Ph 

(S,E)-78 99.1% ee 

( ) 5 

SiMe 2Ph 

(R,E)-78 95.4% ee 

[(S,E)-1-Hexylbut-2-enyl]dimethylphenylsilane [(S,E)-78]; Typical Procedure: [138,140] 

To Pd(acac) 2 (1.4 mg, 4.5 ” 10 ±3 mmol) placed in a Schlenk tube was added 1,1,3,3-tetramethylbutyl 

isocyanide (3.2 ” 10 ±3 mL, 1.8 ” 10 ±2 mmol) at rt. The mixture was stirred for 

15 min at rt. To the vivid red catalyst that formed was added toluene (0.4 mL) and disilane 

(R,E)-75 (99.7% ee; 107 mg, 0.23 mmol) at rt. The mixture was refluxed with stirring for 2 h. 

After the mixture had cooled to rt, the solvent was removed in vacuo. To a soln of the residue 

in THF (0.5 mL) was added 1.6 M BuLi in hexane (0.21 mL, 0.34 mmol) at 0 8C. After the 

mixture had stirred at 08C for 30 min, sat. aq NH 4Cl was added. Extraction with Et 2O followed 

bycolumn chromatography(silica gel, hexane) afforded (S,E)-78 (99.1% ee); yield: 

56 mg (90%). 

4.4.40.21 Method 21: 

Formation of Bis(allylsilanes) from 1,3-Dienes 

Bis(allylsilanes) 80 have been prepared with complete control of regio- and stereoselectivity 

from 1,3-dienes by a palladium-catalyzed dimerization±disilylation reaction (Scheme 

36). [141] It should be noted that this procedure yields exclusively E-1,4 head-to-head dimeric 

allylsilanes from 2-substituted 1,3-dienes. [141] 

Scheme 36 Synthesis of Bis(allylsilanes) [141] 

R 1 

79 

+ 



Me 3Si SiMe 3 

Pd(dba) 2 

DMF, rt, 40 h 

R1 = H 71% 

R1 = Me 85% 

R1 = Ph 82% 

Me 3Si 


R 1 

BuLi 

80 

R 1 

SiMe 3


A mixture of diene 79 (3 mmol), Me 3SiSiMe 3 (73 mg, 0.5 mmol), Pd(dba) 2 (14 mg, 

0.025 mmol), and DMF (2 mL) was placed under an argon flow in a 20-mL flask and stirred 

for 40 h at rt. Then the mixture was passed through a short Florisil column to give a clear 

colorless soln. The product was isolated byMPLC [silica gel, 45±75 ìm (Wakogel 300), hexane] 

followed byKugelrohr distillation. 

(2E,6E)-3,6-Dimethyl-1,8-bis(trimethylsilyl)octa-2,6-diene (80, R 1 = Me); yield: 85%; bp 

908C (bath)/0.3 Torr. 

(2Z,6Z)-3,6-Diphenyl-1,8-bis(trimethylsilyl)octa-2,6-diene (80, R 1 = Ph); yield: 82%; bp 

1158C (bath)/0.3 Torr. 

4.4.40.22 Method 22: 

From Allyl Esters or Allyl Carbamates and a Silylcuprate Reagent 

Allylsilanes are accessible by substitution reactions of allylic alcohol derivatives, such as 

allyl acetates, benzoates, and halides, with a (dimethylphenylsilyl)cuprate [142±149] or related 

reagent. [150,151] Allyl carbamates are also amenable to this method, but, in this case, a 

modified protocol is used, involving the assemblage of a mixed (dimethylphenylsilyl)cuprate 

on the leaving group. [142±144] (Dimethylphenylsilyl)cuprate, used in this protocol, 

unfortunatelyhas some undesirable features, including the formation of nonvolatile 

silicon-containing byproducts, both during preparation of the allylsilanes and in their 

subsequent reactions. [145] In spite of this, the dimethylphenylsilyl group is a good replacement 

for the trimethylsilyl group in practically all reactions of allylsilanes. Incidentally, 

use of mixed cuprates such as [(dimethylphenylsilyl)methyl]cuprate may eliminate or 

minimize silicon-containing byproducts and thereby improve the efficiency of the reaction. 

[145] 

4.4.40.22.1 Variation 1: 

From Allyl Esters 

Allylsilanes have been prepared by treatment of allyl esters with a (dimethylphenylsilyl)cuprate 

reagent. For displacement reactions of primary allylic esters, the formal S N2 

products are preferentiallyformed. [144] Secondaryand tertiaryallylic esters are also amenable 

to this method. [144,146] While displacement reactions of secondaryallylic esters occur 

onlyin a mixture of tetrahydrofuran and ether, [144] tertiaryallylic esters react readilyin 

tetrahydrofuran alone. [146] Allylic substitution reactions of secondary allylic acetates usuallyresult 

in both regioisomers of the allylsilanes; however, the substitution reaction 

favors positioning of the silyl group at the less hindered end of the allylic system, with 

allylic shift especially when Z-allylic acetates are used. This is evident by a comparison 

of the reactions of acetates (E)- and (Z)-81 (Scheme 37). [144] The reaction of tertiaryallylic 

acetates, however, leads exclusivelyto the formation of formallyS N2¢-like products, 

where the silyl group ends up at the less hindered site of the allylic system, for example, 

in the preparation of 84. [146] 

Scheme 37 Allylsilanes from Allyl Esters and Silylcuprate Reagents [144,146] 

Ph 

OAc 

(E)-81 



Li2[Cu(CN)(SiMe2Ph) 2] 

THF, Et2O Ph 

SiMe2Ph 

(E)-82 

+ 

68:32 


Ph 

83 

SiMe2Ph 


OAc 

Ph 

(Z)-81 

OAc 

Li2[Cu(CN)(SiMe2Ph)2] 

THF, Et2O 

Li[Cu(SiMe2Ph)2] 

THF, 0 oC to rt 

93% 

PhMe2Si 

Ph 

(Z)-82 

84 

+ 

18:82 

SiMe 2Ph 

Ph 

83 

SiMe2Ph 

The substitution reactions of allylic acetates take place with anti stereospecificity; examples 

include the respective preparations of silanes 85 [143] and 86 [147,148] (Scheme 38). From a 

mechanistic point of view, no general information is available as to how the regioselectivities 

of the reactions should be rationalized. However, it is probable that these reactions 

involve incompletelyequilibrating ó-allyl±copper(III) intermediates, presumably generated 

by anti oxidative cuprate addition to allyl esters, which then undergo fast reductive 

elimination. [144,152] 

Scheme 38 Allylsilanes from Allyl Esters with Stereochemical Inversion [143,147,148] 

Ph 

Li2[Cu(CN)(SiMe2Ph) 2] 

THF, Et2O OBz PhMe2Si 85 

OAc Li2[Cu(CN)(SiMe2Ph) 2] 

THF, Et2O Ph 

86 

SiMe2Ph 

(2-Cyclopentylideneethyl)dimethylphenylsilane (84); Typical Procedure: [146] 

1-Vinylcyclopentyl acetate (2.3 g, 15 mmol) in THF (20 mL) was added to a stirred soln of 

Li[Cu(SiMe 2Ph) 2] (20 mmol) in THF (140 mL) at 08C under a N 2 atmosphere; subsequently, 

the mixture was kept at 08C for 1 h and at rt overnight. The product was obtained byaqueous 

workup, extraction with pentane, column chromatography(silica gel, petroleum 

ether), and distillation; yield: 3.2 g (93%); bp 102±1048C/0.5 Torr. 

4.4.40.22.2 Variation 2: 

From Allyl Carbamates 



An improved synthesis of regio- and stereodefined allylsilanes from secondary allyl alcohols 

makes use of the corresponding carbamate derivatives. For example, the regioisomeric 

cis allyl carbamates give the regioisomeric allylsilanes 83 and (E)-82 (Scheme 

39); [142±144] note that in the alternative procedure (Scheme 37, Section 4.4.40.22.1), the corresponding 

acetate (Z)-81 gives a mixture of regioisomeric allylsilanes 82 and 83, with the 

latter predominating. The variation here involves generation of a N-bound mixed silylcuprate, 

formed byinitial deprotonation of the carbamates and successive exposure to 

copper(I) iodide and (dimethylphenylsilyl)lithium, from which the silyl group is delivered 

internallyto the ã-carbon. [144,152] Mechanistically, it is believed that the N-bound mixed cuprate 

undergoes a cyclic intramolecular oxidative addition of the ã-carbon to copper, to 

give a copper(III)±ó-allyl complex which undergoes reductive elimination to give syn-ã-silylated 

products. [144,152] 


Scheme 39 Allylsilanes from Allyl Carbamates [142±144] 

Ph 

PhHNOCO 

Ph 

OCONHPh 

1. BuLi, THF 

2. CuI, Ph3P, Et2O 

3. PhMe2SiLi, THF 

68% 

1. BuLi, THF 

2. CuI, Ph3P, Et2O 

3. PhMe2SiLi, THF 

75% 

Ph 

Ph 

83 

SiMe 2Ph 

(E)-82 

SiMe2Ph 

In contrast to the reaction with allylic acetates, syn stereospecificityis observed in the reactions 

of the allylic carbamates, for example, in the formation of silanes 85 and 86A 

(Scheme 40). [143,144] 

Scheme 40 Allylsilanes from Allyl Carbamates with Stereochemical Retention [143,144] 

Ph 

1. BuLi, THF 

2. CuI, Ph3P, Et2O 3. PhMe2SiLi, THF 

OCONHPh PhMe2Si 85 

OCONHPh 



1. BuLi, THF 

2. CuI, Ph3P, Et2O 3. PhMe2SiLi, THF 

Ph 

86A 

SiMe2Ph 

Conversion of Allyl Carbamates into Allylsilanes; General Procedure: [144] 

Under argon at 08C, or, better, in some cases, at ±788C, 1.5 M BuLi in hexane (2.2 mL, 

3.3 mmol) was added to the appropriate carbamate (3 mmol) in THF (5 mL), and the mixture 

was stirred for 1 min. It was then transferred to a flask containing CuI (590 mg, 

3.1 mmol) and Ph 3P (1.6 g, 6.2 mmol) in Et 2O (5 ml) under argon at 08C and stirred for 

30 min. Then 1 M Me 2PhSiLi in THF (4.6 mL, 4.6 mmol) was added to the mixture, which 

was then stirred for a further 2 h. Aq NH 4Cl (30mL) was added to the mixture, which was 

then extracted with Et 2O (2 ” 30 mL). The combined Et 2O extracts were washed with brine, 

dried (MgSO 4), and concentrated in vacuo. The residue was chromatographed (silica gel, 

hexane) to give the allylsilane product. 

Dimethyl[(E)-1-methyl-3-phenylallyl]phenylsilane (83); yield: 68%. 

Dimethylphenyl[(E)-1-phenylbut-2-enyl]silane [(E)-82]; yield: 75%. 

4.4.40.23 Method 23: 

From Allyl Halides and a Silylcopper Reagent 

Allylsilanes have been prepared from allylic halides by allylic substitution with predominant 

or exclusive allylic shift; for this, a reagent presumed to be (trimethylsilyl)copper(I), 

derived from 1 equivalent each of (trimethylsilyl)lithium (from Me 3SiSiMe 3 and 1 equiv 

MeLi·Et 2O in HMPA) and copper(I) iodide in dimethyl sulfide, has been used. 1-Substituted 

allyltrimethylsilanes, for example, 87 and 32, are obtainable in good yield by this method 

(Scheme 41). [153±155] Like (trimethylsilyl)lithium (Section 4.4.40.25), the (trimethylsilyl)copper(I) 

reagent can also be used for the preparation of allylsilanes from secondary allylic 

phosphates. [156] 



Scheme 41 Allylsilanes from Allyl Halides and (Trimethylsilyl)copper(I) [155] 

( ) 5 

Cl 



TMSCu 

87% 

( ) 5 

SiMe3 

Ph 

TMSCu 

Ph Cl + Ph SiMe3 80% 

SiMe3 32 

87 

94:6 

+ 

98:2 

( )5 

44 

55 R 1 = H; R 2 = Ph 

(1-Hexylallyl)trimethylsilane (87); Typical Procedure: [155] 

MeLi·LiBr complex in Et 2O (2.5 mmol) was added dropwise to a soln of Me 3SiSiMe 3 

(365 mg, 2.5 mmol) in HMPA (CAUTION: cancer suspect agent) (3 mL) at 0±5 8C under argon. 

After being stirred for 3 min, the resulting red soln was treated with CuI (476 mg, 

2.5 mmol) in Me 2S (1 mL), and the black mixture was stirred for 3 min. Et 2O (6 mL) was 

added and then the mixture was cooled to ±608C and stirred for 5 min. A soln of 1-chloronon-2-ene 

(160.5 mg, 1 mmol) in Et 2O (1 mL) was added dropwise, and the mixture was 

stirred for 1 h at ±60 to ±508C. The cold soln was poured into petroleum ether (25 mL) 

and sat. aq NH 4Cl (buffered to pH 8 bythe addition of NH 4OH; 25 mL), and the mixture 

was subsequentlyvigorouslystirred for 1 h. The aqueous phase was extracted with petroleum 

ether (3 ”), and the combined organic extracts were dried (MgSO 4), filtered, and concentrated. 

The crude product was purified bycolumn chromatography(silica gel, petroleum 

ether) to afford silanes 87 and 44 [(87/44) 98:2]; total yield: 172 mg (87%). 

SiMe 3 

4.4.40.24 Method 24: 

Formation of 2-Substituted Allylsilanes by Silylcupration of Allene 

2-Substituted allylsilanes have been prepared by silylcupration of allene by (dimethylphenylsilyl)copper(I) 

reagent 88, followed byconjugate addition of the resultant allylsilane/vinylcopper 

intermediate 89 with á-enones in the presence of boron trifluoride±diethyl 

ether complex as additive; this method has been used for the preparation of, for example, 

allylsilanes 90 and 91 (Scheme 42). [157] Use of the boron trifluoride±diethyl ether 

complex is not mandatoryhere, but its presence significantlyincreases the yields of the 

products. [157,158] Besides 1,4-addition, the allylsilane/vinylcopper intermediate 89 also 

takes part in a number of other reactions, including alkylation and acetylation, to give a 

range of allylsilanes. [158] 


Scheme 42 2-Substituted Allylsilanes by Silylcupration of Allene [157] 

PhMe 2Si 

PhMe2SiCu LiCN 88 

THF, −40 oC, 1 h 

89 

Cu 

1. BF3 OEt2, −78 oC, 10 min 

Ph O 

2. , −40 oC, 1 h 

1. BF 3 OEt 2 

2. 

89% 

O 

PhMe2Si 

O 

Ph O 

90 

91 

SiMe2Ph 

Allylsilanes are also available by silylcupration of allenes with lithium bis(dimethylphenylsilyl)cuprate; 

however, the scope of this method is limited. [159,160] 

5-[(Dimethylphenylsilyl)methyl]-4-phenylhex-5-en-2-one (90); Typical Procedure: [157,161] 

A soln of Me 2PhSiLi (3 mmol), prepared in THF (3 mL), was added bysyringe to a stirred 

suspension of CuCN (269 mg, 3 mmol) in THF (5 mL) at 08C. The black mixture was stirred 

at this temperature for an additional 30 min, and the resulting soln of (dimethylphenylsilyl)copper(I) 

complex 88 (3 mmol) in THF (8 mL) was cooled to ±408C and a slight excess of 

allene was added from a balloon. After 1 h of reaction at this temperature, the mixture 

was cooled to ±788C, BF 3 ·OEt 2 (0.38 mL, 3 mmol) was added, and the mixture was stirred 

for another 10 min. The resulting mixture was warmed to ±408C and then (E)-4-phenylbut- 

3-en-2-one (526 mg, 3.6 mmol) in THF (5 mL) was added dropwise at ±408C; the resulting 

soln was kept at this temperature for 1 h. After gentle warming to 0 8C (over 0.5 h), the 

mixture was quenched with sat. aq NH 4Cl and extracted twice with Et 2O. The organic 

phase was dried (MgSO 4) and the solvent was removed under reduced pressure in a rotary 

evaporator. The crude product was purified byflash chromatography(silica gel, 

EtOAc/hexane 1:20) to give a colorless oil; yield: 860 mg (89%). 

4.4.40.25 Method 25: 

From Allyl Halides or Allyl Phosphates and a Silyllithium Reagent 

Allyltrimethylsilanes are available by allylic substitution of allyl halides or phosphates by 

(trimethylsilyl)lithium (from Me 3SiSiMe 3 and MeLi·Et 2O in HMPA) in diethyl ether at low 

temperature. [80,154±156] Although undesirable, hexamethylphosphoric triamide is essential 

for the preparation of trimethylsilyllithium and cannot be replaced by dimethylpropylene 

urea. [162] This method does not appear to be viable with allylic substrates containing 

reactive functional groups. 

4.4.40.25.1 Variation 1: 

From Allyl Halides 



Terminal allylsilanes with control of regio- and stereochemistry can be prepared by silylation 

of primary allylic halides by trimethylsilyllithium in a mixture of diethyl ether and 

hexamethylphosphoric triamide at low temperature, as in, for example, the formation of 



allylsilane 44 (Scheme 43). [154,155] Under these conditions, secondaryallylic halides, for example, 

92, still give terminal E-allylsilanes, albeit contaminated with their regioisomers. 

[155] 

Regio- and stereodefined 3,3-disubstituted terminal allylsilanes have been prepared 

from other silyllithium reagents, such as (dimethylphenylsilyl)lithium; hexamethylphosphoric 

triamide is not required in these reactions, since the silyllithium reagents are prepared 

in tetrahydrofuran. [163] 

Scheme 43 Allylsilanes from Allyl Halides and Trimethylsilyllithium [80,154,155] 

( ) 5 

( ) 8 

Cl 

92 

Cl 

TMSLi, Et 2O, HMPA 

78% 

TMSLi, Et 2O, HMPA 

Trimethyl[(E)-non-2-enyl]silane (44); Typical Procedure: [155] 

MeLi·LiBr complex in Et 2O (1.6 mL, 2.5 mmol) was added dropwise to a soln of Me 3SiSiMe 3 

(365 mg, 2.5 mmol) in HMPA (CAUTION: cancer suspect agent) (3 mL) at 0±5 8C under argon. 

After stirring for 3 min, the resulting red soln was diluted with Et 2O (6 mL), cooled to 

±60 8C, and stirred for 5 min. The color of the mixture changed from orange to yellow during 

this time. A soln of 1-chloronon-2-ene (160 mg, 1 mmol) in Et 2O (1 mL) was added dropwise, 

and the mixture was stirred for 1 h at ±60 to ±50 8C. The cold soln was poured into 

pentane (50 mL) and sat. aq NH 4Cl (50 mL); the aqueous phase was extracted with petroleum 

ether (3 ” 25 mL), and the combined organic extracts were dried (MgSO 4), filtered, 

and concentrated. Purification bycolumn chromatography(silica gel, petroleum ether) 

gave allylsilane 44; yield: 155 mg (78%). 

4.4.40.25.2 Variation 2: 

From Allyl Phosphates 

Treatment of allylic phosphates with trimethylsilyllithium also gives allylsilanes, for 

example, (E)-11 (Scheme 44). [156] Allylic phosphates have advantages over allylic halides, 

especiallywith secondaryallylic substrates, for example, phosphate 93 used in the preparation 

of silane 94. An additional advantage is that most allylic phosphates are stable 

substrates and readily available from allylic alcohols in high yield. [164] 

( ) 8 

( )5 

SiMe 3 

44 

+ 

19:81 

SiMe 3 

Scheme 44 Allylsilanes from Allyl Phosphates and Trimethylsilyllithium [156] 

OPO(OEt)2 

93 



OPO(OEt) 2 

TMSLi, Et2O, HMPA 

−50 to −60 oC, 1 h 

59% 

TMSLi, Et2O, HMPA 

−50 to −60 oC, 1 h 

94 

( )8 

SiMe 3 


SiMe 3 

(E)-11 

SiMe 3



b[(E)-3-Cyclohexylallyl]trimethylsilane (94); Typical Procedure: [156] 

Et 2O (7 mL) was added to a vigorouslystirred red soln of Me 3SiLi (2.5 mmol) in HMPA 

(CAUTION: cancer suspect agent) (3 mL) at 0±58C under argon. The mixture was cooled to 

±60 to ±508C and stirred 2±3 min, and allylic phosphate 93 (275 mg, 1.0 mmol) was added 

in Et 2O (1 mL). The mixture was stirred for 1 h at that temperature. The cold soln was 

poured into petroleum ether and sat. aq NH 4Cl. The aqueous phase was extracted with petroleum 

ether and the combined organic extracts were washed with H 2O, dried, and concentrated. 

The crude product was purified bycolumn chromatography(silica gel, petroleum 

ether); yield: 115 mg (59%). 

4.4.40.26 Method 26: 

Formation of 1,3-Disubstituted Allylsilanes by Decarboxylative Elimination 

Allylsilanes with substituents at both the 1- and 3-positions have been prepared from âsilyl 

esters by a stepwise protocol involving aldol condensation with an aldehyde, followed 

byester cleavage and stereospecific decarboxylative elimination of the resultant 

hydroxy acids. Thus, treatment of â-silyl ester 96 with lithium diisopropylamide gives Zenolate 

(Z)-97, which on exposure to an aldehyde provides â-hydroxy ester 98 (1,2-syn,2,3anti) 

with remarkable stereocontrol over three contiguous stereogenic centers (Scheme 

45). [165,166] Hydroxy acid 99, available from 98 by hydrogenolysis (R 2 = Bn), or cleavage by 

a cuprate (R 2 = allyl), or with tetrabutylammonium fluoride (R 2 =CH 2CH 2SiMe 3), [167] is then 

subjected to stereospecific decarboxylative elimination. While use of dimethylformamide 

dimethyl acetal in refluxing chloroform (Method A) gives the E-allylsilane by anti 

decarboxylative elimination, exposure to benzenesulfonyl chloride in pyridine, followed 

byrefluxing in collidine of the resulting â-lactone 100 (Method B), yields the Z-allylsilane 

by syn elimination (Scheme 45). 

â-Silyl esters 96 have been prepared byconjugate silylcupration of á,â-unsaturated 

esters 95. The esters can also be prepared with high levels of enantiopuritybyconjugate 

addition of the silylcuprate reagent to á,â-unsaturated imides carrying chiral auxiliaries, 

[168,169] or if carbon cuprates are added to â-silyl-á,â-unsaturated N-acylsultams. [170] Incidentally, 

the one-pot synthesis of diastereomeric â-hydroxy ester 98 (1,2-anti,2,3-anti)is 

possible bydirect conjugate addition of 95 and trapping of the resulting E-enolate (E)-97 

with an aldehyde. However, the former procedure via (Z)-97 is preferred, as this entails 

higher diastereoselectivitywith respect to the aldol geometry. 



Scheme 45 Formation of 1,3-Disubstituted Allylsilanes by Decarboxylative Elimination 

[165,166] 

R 1 

95 

CO 2R 2 

LDA, −78 o C 

1. Li2[Cu(CN)(SiMe2Ph) 2] 

2. NH4Cl PhMe 2Si OR 2 

R 1 

(Z)-97 

ester cleavage R 1 

R 3 

R 1 

OLi 

SiMe 2Ph 

99 

R 1 

CO 2H 

OH 

SiMe2Ph 

96 

CO 2R 2 

R 3 CHO R 1 

Method A 

Me2NCH(OMe) 2 

CHCl3, reflux, 5 h 

SiMe 2Ph 

R 1 R 3 Method Configuration 

of 101 

R 3 

Method B 

PhSO2Cl, py 

0 oC, 12 h 

R 3 

SiMe 2Ph 

3 

2 

1 

98 

CO 2R 2 

OH 

R 1 

R 1 

SiMe2Ph O 

R3 100 

R 3 

O 

collidine 

reflux 

SiMe 2Ph 

(E)-101 (Z)-101 

Yield (%) a 

of 101 

Ph Me A E 85 [165] 

Ph Me B Z 51 [165] 

Me Ph A E 87 [165] 

Me Ph B Z 81 [165] 

Me iPr A E 91 [165] 

b [165] 

Me iPr B Z 47 

iPr Me A E 88 [165] 

c [165] 

iPr Me B Z 59 

a From 99. 

b 16% E contamination. 

c 11% E contamination. 



Conversion of â-Hydroxy Acids 99 into E-Allylsilanes (E)-101; Method A; 


Me 2NCH(OMe) 2 (0.72 g, 6 mmol) and â-hydroxy acid 99 (1 mmol) were refluxed in dry 

CHCl 3 (20 mL) for 5 h. The solvent was removed in vacuo and the residue was flash chromatographed 

(silica gel, hexane) to give the E-allylsilane. 

Dimethylphenyl[(E)-1-phenylbut-2-enyl]silane [(E)-101, R 1 = Ph; R 3 = Me]; yield: 85%. 


Ref

Conversion of â-Hydroxy Acids 99 into Z-Allylsilanes (Z)-101; Method B; 


PhSO 2Cl (0.35 g, 2 mmol) was added to a suspension of â-hydroxy acid 99 (1 mmol) in 

anhyd pyridine (7 mL) at 08C. The mixture was shaken well, sealed, and kept in the refrigerator 

overnight. It was then poured onto crushed ice (25 g) and extracted with Et 2O 

(3 ” 20 mL). The combined ethereal extracts were washed with 1 M aq HCl (10 mL), sat. aq 

NaHCO 3 (10 mL), and brine, dried (MgSO 4), and concentrated in vacuo. The residue was 

flash chromatographed (silica gel, hexane/EtOAc 10:1) to give lactone 100. 

â-Lactone 100 (0.48 mmol) in 2,4,6-collidine (4 mL) was refluxed for 4±5 h under N 2. 

The soln was then diluted with Et 2O (20 mL), washed with 1 M aq HCl (3 ” 10 mL), sat. aq 

NaHCO 3 (10 mL), and brine, dried (MgSO 4), and concentrated in vacuo. The residue was 

flash chromatographed (silica gel, hexane) to give the Z-allylsilane. 

Dimethylphenyl[(Z)-1-phenylbut-2-enyl]silane [(Z)-101, R 1 = Ph; R 3 = Me]; yield: 51%. 

4.4.40.27 Method 27: 

Formation of 1-Substituted Allylsilanes by Grieco Dehydration 

1-Substituted allylsilanes 104 have been prepared from silylated primary alcohols 103 by 

Grieco dehydration involving treatment with 2-nitrophenylselenocyanate and hydrogen 

peroxide (Scheme 46). [171] When a cyclohexane or cyclopentane ring spans the â-position 

in 102, preparation of the corresponding silylated primary alcohol 103 requires use of an 

alkylidene malonate instead of acrylate 102 as starting material; such double activation is 

essential for initial conjugate silyl cupration. Although not inexpensive, this method provides 

one of the few routes for the synthesis of 1,1-disubstituted allylsilanes. 

Scheme 46 Formation of 1-Substituted Allylsilanes by Dehydration [171] 

R 2 CO 2R 3 

R 1 

102 

PhMe 2Si 

R 1 R 2 

R 4 

Se 



NO 2 

R 1 R 2 

PhMe 2Si OH 

R 4 

103 

1. H2O2, CH2Cl2, py 

2. aq NaHCO3 

2-O2NC6H4SeCN 

Bu3P, THF, rt 

R1 = Me; R2 = R4 = H 50% (from 103) 

R1 = R2 = Me; R4 = H 51% (from 103) 

R1 = R4 = Me; R2 = H 65% (from 103) 

PhMe 2Si 

R 1 R 2 


Bu 3P (1.2 g, 6 mmol) was added over 5 min to a stirred soln of alcohol 103 (5 mmol) and 2- 

O 2NC 6H 4SeCN (1.36 g, 6 mmol) in dryTHF (50 mL) at rt under N 2. Stirring was continued 

for a further 1 h. The solvent was removed in vacuo and the crude selenoxide was redissolved 

in CH 2Cl 2 (50 mL) containing pyridine (791 mg, 10 mmol). Then 30% H 2O 2 (5.7 mL, 

50 mmol) was added over 10 min at 0 8C; after the soln had been allowed to warm to rt, 

stirring was continued for 24 h. H 2O (50 mL) was added and the organic layer was washed 

with aq NaHCO 3 (25 mL), aq CuSO 4 (25 mL), and brine (25 mL), dried (Na 2SO 4), and the solvent 

was removed in vacuo. Flash chromatography(silica gel, petroleum ether/EtOAc 

10:1) gave allylsilane 104. 

Dimethyl(1-methylallyl)phenylsilane (104, R 1 = Me; R 2 =R 4 = H); yield: 50%; bp 48± 

528C/0.2 Torr. 

(1,1-Dimethylallyl)dimethylphenylsilane (104,R 1 =R 2 = Me; R 4 = H); yield: 51%; bp 58± 

658C/0.2 Torr. 


104 

R 4 


4.4.40.28 Method 28: 

From Alkynes and á-Silyl Organocopper Reagents 

Functionalized allylsilanes have been prepared by carbocupration of alkynes with á-silylated 

organocopper reagents, generated in situ from silylated Grignard reagents such as 

[(trimethylsilyl)methyl]magnesium chloride or the corresponding organolithium reagents, 

followed bytrapping of the resultant ã-silylated vinylcopper intermediates with 

electrophiles. [172±176] Thus, allylsilane 106 [173] can be obtained bythe treatment of ethoxyalkyne 

105 with an organocopper reagent (Scheme 47). Similar reactions on allenic sulfones 

give 2-[(trimethylsilyl)methyl]allylic sulfones. [177] However, in some specific cases, 

such as á-acetylenic and -allenic oxiranes, á-allenic methanesulfonates, or the disulfonate 

107, the carbocupration reaction gives products resulting from double 1,3-substitution 

(1,3 with respect to each sulfonate group), bynucleophilic attack of the copper atom, 

followed byreductive elimination; an example of this procedure is the preparation of 

valuable conjunctive reagent 108, presumablybytwo successive 1,3-substitution reactions. 

[172] In general, two variations of this carbocupration process have been used, for 

the one, a stoichiometric amount of copper(I) salt is used, and the other is a catalytic version. 

Scheme 47 Allylsilanes by Carbocupration of Alkynes [172,173] 

OEt 

1. Me3SiCH2Cu MgClBr 

2. NH3 buffer 

OEt 

105 106 

MsO OMs 

107 



SiMe3 

Me 3SiCH 2Cu MgClBr LiBr (2 equiv) 

4.4.40.28.1 Variation 1: 

Stoichiometric Carbocupration with a Copper(I) Salt 

Carbocupration of alk-1-ynes with á-silylated organocopper reagents, prepared in situ 

from [(trimethylsilyl)methyl]magnesium chloride and an equimolar amount of purified 

copper(I) salt, gives synthetically useful and thermally stable ã-silylated vinylcopper intermediates; 

the latter undergo a range of reactions including hydrolysis, iodination, carbonation, 

oxidative dimerization, alkylation, and so forth, to provide functionalized allylsilanes 

with retention of geometryof the C=C bond. [172,173,178] This is exemplified bythe 

preparation of allylsilanes 111 and 112 from alkyne 109 via the ã-silylated vinylcopper 

species 110 (Scheme 48). [178] Incidentally, allylsilanes derivable from the E-stereoisomer 

of 110 have been prepared by a similar carbocupration of trimethyl(prop-2-ynyl)silane, [173] 

as in the related zirconium-promoted carbometalation process. [80] 


SiMe3 

OMs 

Me 3Si 

108 

SiMe 3

Scheme 48 Allylsilanes by Carbocupration with a Stoichiometric Amount of a Copper(I) 

Salt [178] 

109 

Bu 

Me3SiCH2Cu MgClBr LiI 

Et2O 

Cu 

Bu 

110 

SiMe3 

NH3 buffer 

I 

Bu 

111 78% 

(2-Butylallyl)trimethylsilane (111); Typical Procedure: [173] 

To an Et 2O (50 mL) suspension of CuBr (2.2 g, 15 mmol) and 1 M LiI in Et 2O (20 mL, 

20 mmol) was added 0.9 M Me 3SiCH 2MgCl in Et 2O (17 mL, 15 mmol) at 08C. The mixture 

first gave a yellow precipitate and then became a homogeneous pale green soln, which 

was stirred at ±58C for 1 h. After addition of hex-1-yne (109; 1 g, 12.5 mmol), the mixture 

was allowed to warm to 108C and stirred at this temperature for 18 h. The resulting 

brown soln was then hydrolyzed with NH 3 buffer soln (100 mL). The mixture was filtered 

and decanted, and the organic layer was washed with sat. aq NaCl (10 mL) and dried 

(MgSO 4). The solvent was removed under reduced pressure and the residue was distilled 

through a 10-cm Vigreux column; yield: 1.66 g (78%); bp 708C/10 Torr. 

4.4.40.28.2 Variation 2: 

Copper-Catalyzed Carbometalation of Alk-2-yn-1-ols 

Treatment of the magnesium alkoxides of alk-2-yn-1-ols with [(trimethylsilyl)methyl]magnesium 

chloride in the presence of a catalytic amount of freshly purified copper(I) salt in 

diethyl ether gives 2-hydroxymethyl-substituted alk-2-enylsilanes, as in, for example, the 

formation of bifunctional conjunctive reagents 113 (Scheme 49). [173,175,176] Of note is the 

requirement that chloride should be used as the sole halogen for both the organomagnesium 

and copper salts for good yields. [176] 

Scheme 49 Allylsilanes by Copper-Catalyzed Carbometalation of Alk-2-yn-1-ols [175,176] 

R 1 

OH 



1. s-BuMgCl, Et2O, −20 oC, 10 min 

2. Me3SiCH2MgCl, 10% CuCl 

−20 oC to rt, 3 d 

3. NH4Cl buffer (pH 9) 

R 1 

I 2 

SiMe 3 

113 R 1 = Me 64% 

R 1 = SPh 81% 

[(Z)-2-(Hydroxymethyl)but-2-enyl]trimethylsilane (113, R 1 = Me): [176] 

But-2-yn-1-ol (3.5 g, 50 mmol) was added slowly by syringe to 2.0 M s-BuMgCl in Et 2O 

(25 mL, 50 mmol), diluted in Et 2O (120 mL), at ±208C. After this mixture had stirred for 

10 min at ±208C, CuCl (500 mg, 5 mmol) was added all at once, quicklyfollowed bythe 

addition of 0.71 M Me 3SiCH 2MgCl in Et 2O (70 mL, 50 mmol) bycannula. The mixture was 

allowed to reach rt, and was stirred at this temperature for 3 d before being poured into a 

cold (0 8C) pH 9 NH 4Cl buffer soln (450 mL sat. NH 4Cl +50 mL sat. NH 4OH). The aqueous 

phase was separated and extracted with Et 2O (6 ” 70 mL). The combined organic layers 

were dried (MgSO 4), filtered, and concentrated in vacuo. The crude oil was purified by 

Kugelrohr distillation; product 113 was obtained as a clear, colorless oil; yield: 5.03 g 

(64%); bp 768C/ca. 5 Torr. 


OH 

Bu 

112 

SiMe3 

SiMe 3 


4.4.40.29 Method 29: 

From Mixed Vinylcuprates and (Iodomethyl)trimethylsilane or 

Related Reagents 

Allylsilanes, for example, 115 (Scheme 50), are available from reaction of mixed vinyl cuprates, 

obtainable from vinyllithium reagents and 3-methoxy-3-methylbut-1-ynylcopper, 

with (iodomethyl)trimethylsilane or the corresponding trifluoromethanesulfonate 114, 

the latter generallygiving better yields. [179] Use of (iodomethyl)dimethylphenylsilane is 

preferred in cases where volatilityof the product is of concern. The vinyllithium intermediates 

are prepared bya lithium±halogen exchange reaction of vinyl halides, or, alternatively, 

by a Shapiro reaction of triisopropylbenzenesulfonylhydrazones (ªtrisylhydrazonesº) 

[180] of cyclic and acyclic ketones. 

Scheme 50 Allylsilanes from Mixed Vinylcuprates [179] 

O O 

Br 

1. BuLi, THF 

2. 

MeO 



Cu 

O O 

Cu 

MeO 

Me3SiCH2OTf 114 

49% 

O O 

(1,4-Dioxaspiro[4.4]non-6-en-6-ylmethyl)trimethylsilane (115); Typical Procedure: [179] 

To a soln of 3-methoxy-3-methylbut-1-yne (74 mg, 0.75 mmol) in THF (3 mL) at 0 8C, BuLi 

(0.75 mmol) was added dropwise, and the mixture was stirred for 10 min. The resulting 

butynylide anion was added to a stirred suspension of CuI (150 mg, 0.75 mmol) in THF 

(3 mL) at 08C, and the mixture was stirred at 08C for 30 min. This soln was added dropwise 

to a soln of the 2-lithiated cyclopent-2-en-1-one ethylene ketal (0.75 mmol) (prepared from 

the corresponding bromide) in THF (5 mL) at ±788C, and the resulting mixture was stirred 

for 30 min at ±788C. To this a soln of trifluoromethanesulfonate 114 (0.19 g, 0.75 mmol) in 

THF (2 mL) was added dropwise at ±788C. The mixture was stirred at ±788C for 1 h, 

warmed to ±358C, and then stirred at ±358C for 6 h. The mixture was quenched bythe addition 

of sat. aq NH 4Cl soln (1 mL). Standard workup in Et 2O gave an oil, which was chromatographed 

(silica gel), to provide allylsilane 115; yield: 78 mg (49%). 

4.4.40.30 Method 30: 

From Carboxylic Acid Derivatives and an Organocerium Reagent 

by a Peterson-type Reaction 

2-Substituted allylsilanes have been prepared from carboxylic acid derivatives such as 

esters byexposure to a twofold excess of organocerium reagent, prepared in situ from 

[(trimethylsilyl)methyl]magnesium chloride and cerium(III) chloride, followed by a Peterson-type 

elimination of the resultant bis(silylmethyl)carbinols. This method has, for example, 

been used in the formation of silane 116 (Scheme 51). [181] Chiral 2-substituted allylsilanes, 

for example, 117, [182] as well as allylsilanes containing acid-sensitive functional 

groups, for example, 118 [183,184] are also available bythis method (Scheme 51). This procedure 

is equallyapplicable to lactones as substrates, as shown bythe preparation of silane 


115 

SiMe3

119. [183,185] The trick for successful preparation of allylsilanes by this method is to use a 

good-qualityGrignard reagent and anhydrous reaction conditions. [181,185] However, stericallyhighlycongested 

esters, such as adamantane-1-carboxylate do not react under these 

conditions. [181] An analogous procedure using an organocerium reagent derivable in situ 

from [(trimethylsilyl)methyl]lithium and cerium(III) chloride has limited scope, and is 

suitable onlyfor acid chlorides. [186] 

Scheme 51 Allylsilanes from Carboxylic Acid Derivatives [181±185] 

EtO 

CO 2Me 

1. Me 3SiCH 2MgCl, CeCl 3 

2. silica gel 

77% 

OTMS 1. Me3SiCH2MgCl, CeCl3 

OH 

CO2Et 2. NaH 

100% 

O 

116 

117 

SiMe 3 

SiMe 3 

OEt 1. Me3SiCH2MgCl, CeCl3 

2. silica gel 

OEt 

CO2Et 

86% 

EtO SiMe3 

O 



1. Me3SiCH2MgCl, CeCl3 

2. silica gel 

74% 

[(Trimethylsilyl)methyl]magnesium chloride alone can be used for the conversion of carboxylic 

acid derivatives to 2-substituted allylsilanes, [187±192] but the yields are generally low 

and the reactions are substrate dependent. [192,193] For methyl cyclohexanecarboxylate, the 

second Grignard addition fails, because of preferential enolization of the á-silyl ketone 

intermediate. [181,186] With the organocerium reagent, this problem is avoided byvirtue of 

its strong nucleophilicityand low basicity. [194] 

(2-Cyclohexylallyl)trimethylsilane (116); Typical Procedure: [181] 

Powdered CeCl 3 ·7H 2O (1.86 g, 5.0 mmol) was dried at 1508C/0.1 Torr for 2 h. The flask was 

cooled to rt, and vented to a dryN 2 atmosphere. DryTHF (10 mL) was added, and the suspension 

was stirred at rt under N 2 for 2 h. The slurrywas then cooled to ±708C, and 1 M 

Me 3SiCH 2MgCl in Et 2O (5 mL, 5 mmol) was added bysyringe. The cream-colored suspension 

was stirred at ±708C for 1 h, and then methyl cyclohexanecarboxylate (142 mg, 

1 mmol) was added over 2±3 min. Stirring was continued for 2 h at ±708C, and then the 

mixture was allowed to warm to rt overnight. After the reaction had been quenched 

with 1 M HCl (50 mL), the crude á-bis[(trimethylsilyl)methyl] alcohol was isolated by extraction 

with CH 2Cl 2, dried (MgSO 4), and concentrated in vacuo. The product was dehydroxysilylated 

by being stirred with column-chromatography-grade silica gel (1 g) and 

CH 2Cl 2 (10 mL) for 2±3 h. Filtration, followed byflash chromatographyprovided allylsilane 

116; yield: 151 mg (77%). 

HO 

118 

119 

SiMe 3 



4.4.40.31 Method 31: 

From ã-Silylated Allylic Alcohols by a Claisen Rearrangement 

Functionalized allylsilanes have been prepared with exclusive E selectivityfrom ã-silylated 

allylic alcohols by Claisen rearrangement [195±205] of one kind or another, including 

the Johnson ortho ester Claisen rearrangement, [197±199] the Ireland±Claisen rearrangement, 

[200±202] and the Eschenmoser [203±205] variant. Allylsilanes as well as â-silyl carbonyl 

compounds (Section 4.4.41) are available bythese reactions. 

4.4.40.31.1 Variation 1: 

By a Johnson Ortho Ester Claisen Rearrangement 

Ortho ester Claisen rearrangement of ã-silylated allyl alcohols with trialkyl orthoacetate 

gives E-allylsilanes exclusively. Examples include the preparation of chiral allylsilane 121 

with more than 95% enantiopurity(Scheme 52). [198] The substrates in this reaction, for 

example, silane 120 are available by platinum-catalyzed hydrosilylation of appropriate 

acetylenic alcohols, followed by Sharpless kinetic resolution. Chiral trisubstituted E-allylsilanes 

122, as well as their enantiomers, are also available bythis ortho ester Claisen rearrangement 

methodology. [199] In this case, the necessarysubstrates for rearrangement 

are obtained by rhodium(II)-catalyzed silylformylation of a terminal alkyne, followed by 

isomerization and enzymatic resolution. 

Scheme 52 E-Allylsilanes by Johnson Ortho Ester Claisen Rearrangement [198,199] 

Et 

HO 

R 1 

pfb = perfluorobutanoate 



1. PhMe 2SiH, Pt(0) (cat.) 

2. Sharpless kinetic resolution Et SiMe 2Ph 

88% 

PhMe2SiH, CO 

Rh2(pfb) 4 H 

OH 

R 1 

O 

R 1 

SiMe 2Ph 

SiMe 2Ph 

OH 

93% 

120 

MeC(OMe)3 

EtCO 2H (cat.) 

MeC(OMe) 3 

EtCO 2H (cat.) 

Et 

CO2Me SiMe2Ph 

121 

R 

H H SiMe2Ph 1 

I2, benzene 

R1 = Me 81% 

R1 = Ph 79% 

R1 = CH2OH 90% 

O 

R 1 

H 

CO2Me 

SiMe2Ph 

122 

(+)-[(R,E)-1-(Methoxycarbonylmethyl)pent-2-enyl]dimethylphenylsilane (121): [198] 

A mixture of allyl alcohol 120 (1.00 g, 4.55 mmol), MeC(OMe) 3 (0.82 g, 6.82 mmol), and 

EtCO 2H (3 drops) in drytoluene (20 mL) was refluxed for 30 min. The apparatus was then 

rearranged to allow for removal of volatiles bydistillation, and the volume of the mixture 

was reduced to ca. 10 mL. A further portion of MeC(OMe) 3 (0.82 g, 6.82 mmol) and EtCO 2H 

(1 drop) in drytoluene (10 mL) was then added, and the distillation was continued. This 

process of distillation followed byaddition of MeC(OMe) 3 and EtCO 2H was repeated a further 

three times, until no remaining starting material was detected byTLC. After cooling, 


the mixture was washed with sat. aq NaHCO 3 (20 mL), dried (MgSO 4), and concentrated in 

vacuo. Flash chromatography(EtOAc/petroleum ether 2.5:97.5) gave silane 121 as a colorless 

oil; yield: 1.17 g (93%). 

4.4.40.31.2 Variation 2: 

By an Ireland±Claisen Rearrangement 

Ireland±Claisen rearrangement of ã-silylated allyl esters is useful for the preparation of 

vicinallydiastereomeric 1-substituted chiral E-but-2-enylsilanes. In this case, diastereoselectivityis 

dependent on the enolization conditions as well as the configuration of the 

vinylsilane moiety. Thus, under condition A (LDA, TMSCl) (Scheme 53), propionate ester 

123 gives opticallyactive E-but-2-enylsilane anti-125 with favorable anti selectivityvia the 

kineticallycontrolled E-silylketene acetal intermediate 124. [200] However, under condition 

B (LiHMDS, TBDMSCl), the selectivityis reversed in favor of the syn-diastereomer 

(syn-125) via the thermodynamically controlled species 126. [200] For glycolic ester derivatives, 

for example, (E)-127, chelation-controlled formation of (E)-128 gives E-but-2-enylsilane 

129 with syn selectivityregardless of whether condition A (LDA, TMSCl) or C 

(LiHMDS, TMSCl) is used. [200] For the preparation of anti-diastereomers, for example, anti- 

130, use of Z-vinylsilanes, for example, (Z)-127, is recommended. [201] 

Scheme 53 Formation of E-But-2-enylsilanes by Ireland±Claisen Rearrangement [200,201] 

O 

O 

O 

O 

123 

SiMe 2Ph 

SiMe 2Ph 

OMe 

O 

(E)-127 

O 

(Z)-127 

SiMe2Ph 

OMe 



A: LDA 

TMSCl, py 

81% 

B: LiHMDS 

TBDMSCl 

HMPA 

75% 

A: LDA, TMSCl, py 

C: LiHMDS, TMSCl 

C: LiHMDS 

TMSCl 

Me3SiO 

124 

O 

TMSO 

O 

O 

O 

OSiMe 2Bu t 

126 

OTMS 

(Z)-128 

(E)-128 

SiMe2Ph 

SiMe 2Ph 

SiMe 2Ph 

OMe 

SiMe 2Ph 

OMe 

CO2H 

SiMe2Ph 

anti-125 dr 12:1 

CO2H SiMe2Ph syn-125 75%; dr 16:1 

OMe 

CO2H 

SiMe2Ph 

syn-129 A: 84%; dr 20:1 

C: 68%; dr 23:1 

OMe 

CO2Me 

SiMe2Ph anti-130 dr 40:1 

(2S,3S,4E)-3-(Dimethylphenylsilyl)-2-methoxyhex-4-enoic Acid (syn-129); Condition A; 

Typical Procedure: [200] 

To a soln of iPr 2NH (1.23 g, 12.22 mmol) in dryTHF (23 mL) at 08C was added 2 M BuLi in 

hexane (5.75 mL, 11.51 mmol). The soln was stirred at 0 8C for 30 min. After the mixture 

had been cooled to ±788C, a soln of TMSCl (9.85 mL, 77.65 mmol) and pyridine (6.92 mL, 



85.56 mmol) in THF (17 mL) was added. After 5 min, a soln of (E)-127 (2 g, 7.19 mmol) in 

dryTHF (47.9 mL) was added. The soln was stirred at ±788C for 5 min before being warmed 

to 08C for 1 h. The soln was then diluted with 10% aq HCl (50 mL), extracted with EtOAc 

(2 ” 50 mL), dried (MgSO 4), and the solvent was removed in vacuo; this afforded a crude 

yellow oil. Chromatographic purification (silica gel, petroleum ether/EtOAc 1:0 to 1:4) afforded 

hexenoic acid 129 as a clear oil (syn:anti 20:1); yield: 1.68 g (84%). 

(2R,3R,4E)-3-(Dimethylphenylsilyl)-2-methylhex-4-enoic Acid (syn-125); Condition B; 


For the preparation of LiHMDS, 1 M BuLi in hexane (1.53 mL, 1.53 mmol) was added to a 

soln of freshlydistilled TMS 2NH (322 ìL, 1.53 mmol) in dryTHF (3 mL) at 08C. The soln was 

stirred at 08C for 30 min, and was then added to a soln of 123 (200 mg, 0.76 mmol) in dry 

THF (5.06 mL) at ±788C. After 10 min the yellow soln was treated with TBDMSCl (229.5 mg, 

1.53 mmol) in HMPA (CAUTION: cancer suspect agent) (1 mL). The soln was allowed to 

warm to rt over 5 h and then refluxed for 2 h before being diluted with 10% aq HCl 

(50 mL). The soln was extracted with EtOAc (2 ” 50 mL), dried (MgSO 4), and concentrated 

in vacuo to afford a crude yellow oil. This was redissolved in THF (10 mL), and then treated 

with 10% aq HCl (2 mL) at rt and allowed to stir for 2 h. Further dilution with 5% aq HCl 

(10 mL) and extraction with EtOAc (2 ” 20 mL), followed bydrying (MgSO 4), filtration, 

and removal of solvent in vacuo resulted in isolation of a crude orange oil. Chromatographic 

purification (silica gel, petroleum ether/EtOAc 1:0 to 1:4) afforded hexenoic acid 

125 (syn:anti 16:1); yield: 150 mg (75%). 

(2S,3S,4E)-3-(Dimethylphenylsilyl)-2-methoxyhex-4-enoic Acid (syn-129); Condition C; 


To a soln of freshlydistilled TMS 2NH (890 ìL, 4.22 mmol) in dryTHF (8.44 mL) at 0 8C was 

added 1 M BuLi in hexane (4.17 mL, 4.17 mmol). After 30 min at 08C, the soln was added to 

a THF soln of (E)-127 (645 mg, 2.32 mmol) in dryTHF (9.3 mL) at ±788C. The yellow soln 

was allowed to stir for 1 h at ±788C before addition of TMSCl (883 ìL, 6.96 mmol). The 

soln was allowed to warm to rt over 14 h before being diluted with 10% aq HCl (50 mL). 

The mixture was extracted with EtOAc (2 ” 50 mL), dried (MgSO 4), and concentrated in 

vacuo to afford a crude yellow oil. Chromatographic purification (silica gel, petroleum 

ether/EtOAc 1:0 to 1:4) afforded hexenoic acid 129 (syn:anti 23:1) as a clear oil; yield: 

438 mg (68%). 

4.4.40.31.3 Variation 3: 

By the Eschenmoser Variant of the Claisen Rearrangement 

Silanes containing both an amido and allyl functionality and with defined stereochemistryare 

accessible bythe Eschenmoser variant of the Claisen rearrangement of ã-silylated 

allyl alcohols. Thus, using N,N-dimethylacetamide dimethylacetal, the chiral allylsilane 

(R)-132 has been prepared (Scheme 54). [203,204] 

Scheme 54 Allylsilanes by the Eschenmoser Variant of the Claisen Rearrangement [203] 

Me 3Si 

131 

OH 



OMe 

benzene, 90 o Me2N OMe 

C, 13 h 

95% 

Me 2N 

O 

(R)-132 

SiMe3 


(+)-(3R,4E)-N,N-Dimethyl-3-(trimethylsilyl)hex-4-enamide [(R)-132]: [203] 

Alcohol 131 (1.04 g, 7.2 mmol; corrected for 15% contamination with its saturated analogue), 

Me 2NCMe(OMe) 2 (3.1 mL, 20.9 mmol), and drybenzene (15 mL) were heated for 

13 h in a sealed ampule under argon at 908C. Volatile materials were removed and the 

crude product was chromatographed (silica gel, hexane/EtOAc 7:3) and then distilled (Kugelrohr, 

75±80 8C/0.1 Torr) to give hexenamide (R)-132 as a colorless oil; yield: 1.455 g 

(95%; corrected for contamination with starting material). 

4.4.40.32 Method 32: 

From 1-Trimethylsilyl-1,3-dienes by a Diels±Alder Reaction 

Cyclic allylsilanes adorned with a choice of functional groups are accessible by Diels±Alder 

reaction of 1-trimethylsilyl-1,3-dienes with various dienophiles, for example, the 

preparation of allylsilane 134 (Scheme 55). [206±208] The silyl group exerts little directing influence 

on the regioselectivityof the reaction with unsymmetrical dienophiles, this reaction 

being governed byother substituents, if any, present on the dienes. [206±208] Indeed, the 

weak directing effect of the trimethylsilyl group can be completely overwhelmed, as in 

the synthesis of the single regioisomeric allylsilane 135, an intermediate used in a synthesis 

of ( )-shikimic acid. [209] Intramolecular Diels±Alder reactions of substrates with a builtin 

1-silyl-1,3-diene moiety have allowed access to more complex allylsilanes. [210,211] 

Scheme 55 Allylsilanes from Terminally Silylated 1,3-Dienes [206±209] 

SiMe 3 

133 

OAc 

SiMe 3 

O 

+ O 

+ 

O 

CO2Me 



95−100 oC, 30 min 

74% 

Me3Si H 

OAc 

SiMe 3 

135 

H 

134 

CO 2Me 

3-(Trimethylsilyl)cyclohex-4-ene-1,2-dicarboxylic Anhydride (134); Typical Procedure: [208] 

Diene 133 and maleic anhydride were mixed in equimolar amounts, allowing for any codistillate 

with which the diene was contaminated; a crystal of hydroquinone was added, 

and the mixture was stirred at 95±1008C for 0.5 h under N 2. The product was crystallized 

from cyclohexane to give anhydride 134 as plates; yield: 74%; mp 125±1268C. 

4.4.40.33 Method 33: 

Formation of Cyclopentanoid Allylsilanes by an Intramolecular Ene Reaction 

cis-1,2-Disubstituted cyclopentanoid E-allylsilanes, for example, 138, have been prepared 

with high diastereoselectivity by thermolytic ene cyclization of activated 1,6-dienes, for 

example, 136, featuring a homoallylsilane unit as ene donor (Scheme 56). [212,213] Note 

that the yield of this reaction suffers if air is not purged properly with argon. Also, diene 

136 (R 1 =R 3 =H;R 2 =R 4 = Me) fails to give the corresponding silane 138, even at elevated 

temperatures for a longer reaction period. The exclusive formation of E-allylsilanes is 

explicable in terms of transition state 137. The failure of 136 (R 1 =R 3 =H;R 2 =R 4 = Me) towards 

cyclization is presumably due to unavoidable 1,3-diaxial interactions involving a 


O 

O 

O 


methyl group â to the trimethylsilyl group in 137. [213] This procedure is also applicable to 

the preparation of cyclopentanoid allylsilanes containing an oxygen functionality on the 

cyclopentane ring. [214] 

Scheme 56 Cyclopentanoid Allylsilanes by an Intramolecular Ene Reaction [212,213] 

R 3 

R 3 

Me3Si 

R 2 

136 

R 1 

CO2R 4 

heat 

R 3 

R 3 

H 

H 

CO 2R 4 

H 

R 2 

137 

R 1 R 2 R 3 R 4 Conditions Yield (%) 

of 138 

CH(R 1 )SiMe 3 

R 3 

R 3 

R 2 

H 

H 

138 

bp (8C/Torr) 

of 138 a 

R 1 

SiMe3 

CO2R 4 

H H H Et 2528C, 45 h 98 115±120/0.01 [212,213] 

Me H H Me 2438C, 16 h 93 130±131/0.3 [212,213] 

H H Me Et 2458C, 30 h 97 125±130/0.01 [212,213] 

H Me H Me 2438C, 16 h 0 n.r. [212,213] 

a n.r. = not reported. 



Formation of (3-Cyclopentylallyl)silanes 138 by Thermolytic Cyclization of Dienes 136; 


A Pyrex tube containing 5% diene 136 in drytoluene was purged with argon and sealed. 

The tube was heated in a constant-temperature tubular furnace (temperatures and times 

given in Scheme 56). After the mixture had cooled to rt, the solvent was removed in vacuo 

and the residue was distilled to give allylsilane 138. 

4.4.40.34 Method 34: 

From Alkenyl Fischer Carbene Complexes by a [2+1]-Insertion Reaction 

with Triorganosilanes 

A [2+1]-insertion reaction of Fischer carbene complexes with triorganosilanes gives allylsilanes, 

for example, 140, under mild conditions (Scheme 57). [215,216] The reaction is regioselective 

at the metal±carbene bond and shows no significant hydrosilylation at the alkenyl 

site. For more electron-rich â-methoxycarbene complexes, for example, 139 

(R 1 = Ph; R 2 = OMe), the reaction is relativelysluggish, presumablydue to a decrease in 

the electrophilicityof the carbene carbon. At present, this seems to offer the onlyavailable 

route for straightforward preparation of 1-methoxyallylsilanes. 


Ref

Scheme 57 From Alkenyl Fischer Carbene Complexes [215,216] 

R 1 

R2 Cr(CO) 5 

MeO 

139 

Et3SiH, hexane, 60 oC R1 = Ph; R2 = H 68% 

R1 = Ph; R2 = OMe 63% 

Triethyl[(E)-1-methoxy-3-phenylallyl]silane (140, R 1 = Ph; R 2 = H); Typical Procedure: [215] 

Et 3SiH (0.029 g, 0.25 mmol) and carbene complex 139 (R 1 = Ph; R 2 = H) (65 mg, 0.19 mmol) 

were dissolved in hexane (8 mL) in a vacuum-tight Teflon-stoppered flask. The deep-red 

soln was deoxygenated by the freeze±pump±thaw method (3 cycles), then stirred and 

heated to 608C under N 2. After 1 h, the resulting brownish-yellow suspension was concentrated 

under reduced pressure in a rotaryevaporator and purified byflash chromatography(silica 

gel, hexane) to afford the product as a colorless liquid; yield: 34 mg (68%). 

4.4.40.35 Method 35: 

From Vinyldiazo Carbonyl Compounds by a Rhodium-Catalyzed 

[2+1]-Insertion Reaction with Triorganosilanes 

Rhodium-catalyzed decomposition of vinyldiazocarbonyl compounds in the presence of 

triorganosilanes gives the corresponding allylsilanes, for example, E- and Z-allylsilanes 

(E)- and (Z)-142, each containing a useful ester function (Scheme 58). [217,218] Of note is complete 

retention of the C=C bond geometryin the products. Access to enantioenriched allylsilanes 

is possible if either a chiral auxiliary attached to the ester function, or a chiral 

catalyst is used. [217±219] Thus, with the rhodium(II) chiral catalyst 143, allylsilane 144 has 

been prepared with 91% enantiopurity. [219] Use of a nonpolar solvent and low temperature 

are essential for successful asymmetric synthesis with catalyst 143. [219] 

R 1 

R 2 

MeO 

140 

SiEt 3 

Scheme 58 Allylsilanes from Vinyldiazo Carbonyl Compounds [217,218] 

N2 

CO 2Et 

(E)-141 (E/Z) 98:2 

N 2 

CO 2Et 

(Z)-141 (E/Z) 4:96 

N 2 

Ph CO 2Me 



PhMe2SiH 1 mol% Rh2(OAc) 4, CH2Cl2 65% 

PhMe2SiH 1 mol% Rh2(OAc) 4, CH2Cl2 68% 

SiMe2Ph 

CO 2Et 

(E)-142 (E/Z) 98:2 

PhMe 2Si 

CO 2Et 

(Z)-142 (E/Z) 5:95 

O 

N 

Rh 

PhMe2SiH, S O 

O 

O Rh 

143 (cat.) 

pentane, −78 o C 

( ) 11 4 

76% 

SiMe 2Ph 

Ph CO 2Me 

144 91% ee 

[(Z)-1-(Ethoxycarbonyl)pent-2-enyl]dimethylphenylsilane [(Z)-142]; Typical Procedure: [218] 

To a stirred soln of diazo ester (Z)-141 (386 mg, 2.3 mmol) and Me 2PhSiH (625 mg, 

4.6 mmol) in dryCH 2Cl 2 (20 mL) was added Rh 2(OAc) 4 (0.01 mmol) at rt. The mixture was 

stirred at rt for 20 min, and the solvent was removed in vacuo. Kugelrohr distillation of 

the residue gave silane (Z)-142 [containing 5% (E)-142] as a colorless oil; yield: 431 mg (68%). 



4.4.40.36 Method 36: 

Formation of Formyl-Substituted Alk-2-enylsilanes by Photolysis 

Aldehydes containing the allylsilane functionality have been prepared by photolytic ácleavage 

of cyclic ketones bearing a (trimethylsilyl)methyl group in either the á- orâ-position 

(Scheme 59). [220,221] For example, irradiation of ketone 145 (R 1 = H; n = 2) in methanol 

for 18 hours at 08C with a high-pressure mercurylamp with a Pyrex filter (ë > 

2800 Š) gives allylsilane 146 (R 1 = H; n = 2) in 70% yield along with 11% of the saturated ester 

147 (R 1 = H; n = 2). If cyclohexane is used as the solvent, the photolysis proceeds in only 

3 hours, yielding 73% of allylsilane 146 (R 1 = H; n = 2) unaccompanied bysaturated ester 

147 (R 1 = H; n = 2). Irradiation of cyclopentanone 148 proceeds onlyin a mixture of benzene/methanol 

(96.5:3.5), and not in methanol alone, to give the Z-isomer of the formylsubstituted 

branched allylsilane 149 as the major product. Note, however, that photochemicallyinduced 

á-cleavage of the six-membered cyclic analogues of 148 proceeds 

only sluggishly, and the corresponding formyl-substituted alk-2-enylsilanes do not form 

at all under these conditions. 

Scheme 59 Formation of Formyl-Substituted Alk-2-enylsilanes by Photolysis [220,221] 

R 1 

O 

( ) n 

145 

SiMe 3 

MeOH, hν CHO 

R1 SiMe3 + 

( ) n 

MeO2C 

R1 ( ) n 

146 147 

R 1 n Ratio (E/Z)of146 Yield (%) of 146 Yield (%) of 147 Ref 

SiMe 3 

H 1 3.2:1 98 ± [221] 

H 2 >99:

4.4.40.37 Method 37: 

From Allyl Sulfides by Reductive Silylation 

Regio- and stereodefined allylsilanes are available from allyl sulfides bearing a siloxy or 

hydroxy group at an appropriate position. Two variations of this method have been reported; 

in one, an allyllithium species is generated from a siloxy compound, after which 

the silyl group migrates from oxygen to the carbanionic site (reverse Brook rearrangement), 

while the other involves silylation of an oxyanion±carbanionic species. 

4.4.40.37.1 Variation 1: 

By Retro-[1,4]-Brook Rearrangement 

Vicinally diastereomeric 1-substituted allylsilanes containing an oxygen functionality 

have been prepared with high diastereoselectivity from siloxy-substituted allyl sulfides 

subjected to reductive silylation with lithium 4,4¢-di-tert-butylbiphenylide, as in, for example, 

the preparation of anti-allylsilane 151 (Scheme 60). [222] This protocol can also be 

used for the preparation of cyclic allylsilanes bearing a hydroxymethyl and trimethylsilyl 

group in a cis-1,2 relationship, for example, 152. Of note is the 1,2-asymmetric induction 

of alkylated stereocenters in these stereogenic retro-[1,4]-Brook rearrangements. A similar 

level of stereocontrol has also been achieved through the 1,3-asymmetric induction 

of an oxygenated stereocenter connected to either the á- orã-carbon of the allyl sulfide 

backbone bya methylene unit. [223] 

Scheme 60 Allylsilanes by Stereogenic Retro-[1,4]-Brook Rearrangement [222] 

PhS 

SPh 

150 

OTMS 

OTMS 



LDBB 

−78 oC, 0.5−1 h 

93% 

LDBB, THF 

−78 oC, 0.5−1 h 

97% 

SiMe3 

152 dr >99:1 

SiMe3 

151 dr >99: 99:1); yield: 54 mg (97%). 

4.4.40.37.2 Variation 2: 

By Silylation of Oxyanion±Carbanionic Species 

Allylsilanes are available from cyclic allylic sulfides carrying a hydroxymethyl group at a 

proper position bytreating the lithium alkoxides of the sulfides with lithium 4,4¢-di-tertbutylbiphenylide, 

followed by silylation with chlorotrimethylsilane, for example, the 

preparation of trans-substituted allylsilanes 153 and 155 (Scheme 61). [222] Incidentally, 

loss of regioselectivity occurs with cyclic allylic sulfides lacking substituents (other than 


OH 

OH 


the phenylsulfanyl functionality) at either the â-orã-position with respect to the hydroxy 

group, for example, allylic sulfide 156. 

Scheme 61 Allylsilanes by Silylation of Dilithiated Species [222] 

PhS 

PhS 

SPh 

156 

154 

OH 

OH 

OH 

1. BuLi 

2. LDBB 

3. TMSCl 

4. K2CO3 (cat.), MeOH 

53% 

1. BuLi, THF, hexane 

2. LDBB, THF 

3. TMSCl 


83% 

1. BuLi 

2. LDBB 

3. TMSCl 


75% 

Me 3Si 

Me 3Si 

153 dr 99:1 

Me3Si 

155 dr >99: 99:1); yield: 32 mg (83%). 

OH 

75:25 

SiMe3 

4.4.40.38 Method 38: 

From Allyl Sulfides and Tris(trimethylsilyl)silane by a Radical Reaction 

2-Substituted allyltris(trimethylsilyl)silanes have been prepared by substitution of allylic 

sulfides by tris(trimethylsilyl)silanes in the presence of 2,2¢-azobisisobutyronitrile, as, for 

example, in the preparation of allylsilane 158 (Scheme 62). [224] These allylsilanes appear 

to be safe alternatives to allylstannanes in radical-based allylation reactions (see Section 

4.4.40.57), as the end products from such reactions with allylstannanes are frequently 

contaminated with toxic organotin byproducts. It is believed that the reactions leading 

to silanes 158 proceed bya free-radical chain process involving displacement of the aryl 

sulfide by a tris(trimethylsilyl)silyl radical. [224] 

Scheme 62 Formation of 2-Substituted Allyltris(trimethylsilyl)silanes [224] 

R 1 

157 

SPh 

+ 



(Me3Si) 3SiH 

AIBN 

R1 = H 92% 

R1 = Me 84% 

R1 = CO2Et 79% 

R 1 

Si(SiMe3) 3 


158 

OH

Allyltris(trimethylsilyl)silane (158, R 1 = H); Typical Procedure: [224] 

Allyl phenyl sulfide (157, R 1 = H) (30 mg, 0.2 mmol), HSi(SiMe 3) 3 (74 mg, 0.3 mmol), and 

AIBN (10 mol%) were refluxed in benzene for 1 h. The consumption of the starting material 

and the appearance of the products were followed byNMR or GC. Workup with 1 M 

NaOH was followed bycolumn chromatography(silica gel); yield: 53 mg (92%). 

4.4.40.39 Method 39: 

From Allyl Sulfones 

Allylsilanes have been prepared from allyl sulfones by sequential treatment with tert-butyllithium 

and chlorotrimethylsilane, followed by reductive desulfonylation of the resultant 

allylsulfonylsilanes with sodium/N,N-dimethylnaphthalen-1-amine in the presence of 

diethylamine, use of which as proton source improves the yield and the E/Z selectivity. For 

example, allylsilane 161 has been prepared from recrystallized allylsulfonylsilane 160 

(Scheme 63). [225] Note that preparation of allylsilane 161 proved difficult bya host of other 

techniques, including a Grignard reaction (Section 4.4.40.1), methods based on counterattacking 

principles (Section 4.4.40.18), or a Julia reaction (Section 4.4.40.12). [225] The 

allylsulfonylsilanes, for example, 160, can also be generated in situ, and this allows a 

one-pot preparation of allylsilanes directly from allylsulfones. [225] 

Scheme 63 Allylsilanes from Allyl Sulfones [225] 

159 



SO2Ph 

1. t-BuLi, THF, Et2O, −78 oC 2. TMSCl 

80% 

Na/Me2NC10H7, Et2NH THF, −85 oC 84% 

160 

SiMe3 

161 (E/Z) >10:1 

SO2Ph 

Trimethyl[(2E,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienyl]silane and 

Trimethyl[(2Z,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienyl]silane 

(161); Typical Procedure: [225] 

Treatment of allyl sulfone 159 (1 g, 3 mmol) with t-BuLi (1.2 equiv) in THF/Et 2O (1:1; 50 mL) 

at ±788C generated an anion, which reacted with TMSCl (3 equiv) to give silylallyl sulfone 

160 as brown crystals, which could be recrystallized as pale yellow crystals from hexane; 

yield: 0.96 g (80%); mp 113±1148C. 

A soln containing sulfone 160 (0.1 g, 0.24 mmol) dissolved in anhyd THF (1 mL) and 

Et 2NH (0.5 mL, 4.8 mmol) was added under argon at ±858C to a previouslyprepared soln 

of Na/Me 2NC 10H 7 [prepared bystirring Na (8 equiv) in THF (20 mL) with Me 2NC 10H 7 (4 

equiv) at ±108C under argon for 3 h]. Immediatelyafter addition of the allylsulfone to 

this soln at ±858C, distilled H 2O (1 mL), followed byhexane (20 mL) were added. (At this 

point the excess Na was removed from the reaction mixture.) The resulting soln was extracted 

with H 2O (20 mL) and 10% HCl (2 ” 20 mL) to remove the Me 2NC 10H 7. The organic 

solvents were removed under reduced pressure and the residue was purified byflash 

chromatography(hexane) to give a clear oil; yield: 56 mg (84%); bp 1108C/0.4 Torr. 


SiMe 3 


4.4.40.40 Method 40: 

Formation of 3-Substituted Allylsilanes by a Peterson-type Elimination 

Regio- and stereodefined 3-substituted allylsilanes have been prepared by Peterson-type 

elimination reaction of ul-1,2-bis(trimethylsilyl)alkan-3-ols; the base-induced reaction 

gives the Z-isomer, and the acid-catalyzed reaction gives the E-isomer in over 95% stereochemical 

purityin most cases. [57,226] For example, the E-3-substituted allyltrimethylsilanes 

(E)-163 have been obtained byacid-catalyzed elimination of 162, whereas potassium hydride 

induced reaction of 162 gives the corresponding Z-isomers (Z)-163 (Scheme 

64). [57,226] Desilylation products, that is, E- and Z-1-phenylpropenes form with potassium 

hydride only in the case of 163 (R 1 = Ph); this problem can be obviated byuse of sodium 

hydride in place of potassium hydride. [226] The desired bis-silylated alcohols 162 have 

been prepared either from Z-vinylsilanes via the corresponding epoxides and opening of 

the latter [226] with an á-silylated organocuprate, or from (E)-1,3-bis(trimethylsilyl)propene 

via the corresponding epoxide and reaction of the latter [57] with a Gilman reagent. 

Scheme 64 Formation of 3-Substituted Allylsilanes by a Peterson-type Elimination [57,226] 

HO 

H 

R1 162 

SiMe3 H 

SiMe 3 



BF3 OEt2 

R1 = Me 99% (GC) 

R1 = iPr 96% (GC) 

R1 = Bu 92% 

R 1 

SiMe 3 

KH R 1 SiMe3 

R1 = Me 92% (GC) 

R1 = iPr 97% (GC) 

R1 = Bu 85% 

(E)-163 

(Z)-163 

[(Z)-Hept-2-enyl]trimethylsilane [(Z)-163,R 1 = Bu]; Typical Procedure: [226] 

Commercial 35% KH in mineral oil (1.14 g) was washed with pentane (3 ” 15 mL) and dried 

under a stream of N 2. To this was added THF (20 mL), and, to the stirred slurry, 162 

(R 1 = Bu) (2.6 g, 10 mmol) was added dropwise bysyringe. After 1 h at 308C, the mixture 

was centrifuged and the decanted soln was poured into a separating funnel containing a 

mixture of sat. aq NH 4Cl (50 mL) and Et 2O (50 mL). After separation, the organic material 

was dried (K 2CO 3), concentrated in vacuo, and distilled; yield: 1.5 g (85%); bp 888C/55 Torr. 

[(E)-Hept-2-enyl]trimethylsilane [(E)-163, R 1 = Bu]; Typical Procedure: [226] 

BF 3 ·OEt 2 (0.47 g, 3.3 mmol) was added dropwise to a stirred soln of 162 (R 1 = Bu) (2.6 g, 

10 mmol) in CH 2Cl 2 (20 mL) at 08C. After 15 min, the soln was poured into a separating 

funnel containing sat. aq NaHCO 3 (50 mL). After separation, the organic material was 

washed with sat. aq NaHCO 3 (2 ” 50 mL), dried (K 2CO 3), concentrated in vacuo, and distilled; 

yield: 1.57 g (92%); bp 888C/55 Torr. 

4.4.40.41 Method 41: 

Formation of 3-Substituted Allylsilanes by Silicon-Directed 

Bamford±Stevens Reaction 

3-Substituted allylsilanes are available from â-silyl ketones via the corresponding Naziridinylimines 

by a silicon-directed Bamford±Stevens reaction of the latter. Thus, thermolysis 

of â-trimethylsilyl N-aziridinylimines 165 in toluene in the presence of rhodium(II) 

acetate (2 mol%) at 1458C gives allylsilanes 166 containing a major proportion of 


the Z-isomer; very little, if any, of the isomeric homoallylsilanes form under these conditions 

(Scheme 65). [227] The N-aziridinylimines are accessible in high yield by condensation 

of the respective â-silyl ketones with 1-amino-2-phenylaziridinium acetate. 

Scheme 65 3-Substituted Allylsilanes by Silicon-Directed Bamford±Stevens Reaction [227] 

R 1 

O 

164 

SiMe3 

Ph 

N OAc 

NH3 

− 

+ 

CH 2Cl 2, 0 o C, 4 h 

R 1 

N 

Rh 2(OAc) 4 

toluene, 145 o C 

N 

165 

Ph 

SiMe3 

R 1 

SiMe 3 

166 R 1 = (CH 2) 5Me 61%; (E/Z) 14:86 

R 1 = Bn 65%; (E/Z) 14:86 

Dec-2-enyltrimethylsilane [166,R 1 = (CH 2) 5Me]; Typical Procedure: [227,228] 

1-Amino-2-phenylaziridinium acetate (450 mg, 2.32 mmol) was added to a stirred soln of 

ketone 164 [R 1 = (CH 2) 5Me] (352 mg, 1.54 mmol] in CH 2Cl 2 (5 mL) at 08C, and the mixture 

was stirred for 4 h at the same temperature. Ice-cold water (4 mL) was added and the organic 

product was extracted with Et 2O (3 ” 10 mL). The combined organic extracts were 

washed with 10% aq NaHCO 3 (5 mL) and brine (5 mL), dried (MgSO 4), and concentrated in 

vacuo. Preparative layer chromatography (silica gel, EtOAc/petroleum ether 1:39) of the 

residue gave 165 [R 1 = (CH 2) 5Me] as a colorless thick oil, which was taken up in a Pyrex 

glass tube (length/diam 25 cm:2 cm) containing Rh 2(OAc) 4 (13.6 mg, 2 mol%) and toluene 

(10 mL). The tube was then purged with argon, sealed, and heated in an oven at 1458C 

for 2.5 h. After the mixture had cooled to rt, the solvent was removed in vacuo. The product 

was obtained bypreparative layer chromatography(silica gel, petroleum ether) of the 

residue; yield: 199 mg (61%); bp 80±85 8C (bath)/10 Torr. 

4.4.40.42 Method 42: 

From ã-Silylated Allylic Esters or Allyl Carbonates 

by a Palladium(0)-Catalyzed Reduction 

Allylsilanes are available by palladium(0)-catalyzed reduction of ã-silylated allylic esters 

or allylic carbonates. Two procedures have been reported; in the one, allylic esters are 

used as substrates and sodium formate is the hydride source; the other method proceeds 

byreduction of allylic carbonates byformic acid in the presence of an organic base. 

4.4.40.42.1 Variation 1: 

From Allylic Esters 



Hydrogenolysis of ã-silylated allylic esters by sodium formate as hydride source in the 

presence of 15-crown-5 (10 mol%) and 5% of palladium(II) acetate/triphenylphosphine 

(1:2) as catalyst gives allylsilanes as the major products, usually accompanied by minor 

amounts of isomeric vinylsilanes as the byproducts; an example of this is the preparation 

of allylsilane 168 (Scheme 66). [229] For acyclic allylsilanes, for example, 170 and 68, this 

protocol allows some control of double-bond geometry, but is nonetheless plagued by 

considerable amounts of vinylsilanes as unavoidable side products. 



Scheme 66 Allylsilanes from Allyl Esters by Palladium(0)-Catalyzed Reduction [229] 

Et 

SiEt3 

OAc 

1. Pd(OAc)2/Ph3P (cat.) 

THF, rt, 15 min 

2. HCO2Na, 15-crown-5 (cat.) 

rt, 10 h 

86% 

167 168 

OAc 

SiMe 3 

Ph SiMe3 

OAc 

Pd(OAc) 2/Ph3P (cat.) 

HCO2Na, 15-crown-5 (cat.) 

81% 

Pd(OAc) 2/Ph3P (cat.) 

HCO2Na, 15-crown-5 (cat.) 

87% 

SiEt3 

Et SiMe 3 

+ 

96:4 

169 

170 (E/Z) 70:30 68:32 30 

68 (E/Z) 99:1 

+ 

Pr 

SiEt3 

SiMe3 

Ph SiMe3 + Ph 

SiMe3 (2-Cyclohexylideneethyl)triethylsilane (168); Typical Procedure: [229] 

A soln of allylic acetate 167 (134 mg, 0.5 mmol) in THF (2 mL) was stirred under argon with 

a soln of Pd(OAc) 2 (5.6 mg, 0.025 mmol) and Ph 3P (13.1 mg, 0.05 mmol) in THF (2 mL). After 

stirring at rt for 15 min, the resultant soln of ð-allylpalladium(0) complex was added to a 

mixture of HCO 2Na (102 mg, 1.5 mmol) and 15-crown-5 (11 mg, 0.05 mmol). The mixture 

was stirred at rt for 10 h until complete disappearance of the starting material (monitored 

byTLC). Then pentane (30 mL) and H 2O (5 mL) were added, the mixture was filtered 

through Celite, and the organic phase was washed with H 2O (5 ” 5 mL), dried (Na 2SO 4), 

and concentrated. Chromatographic purification (silica gel, hexane) of the residue gave 

the product (168/169 96:4); total yield: 90 mg (86%). 

4.4.40.42.2 Variation 2: 

From Allylic Carbonates 



Allyl carbonates carrying both a silyl and an alkyl or aryl group at the 3-position are readilyreduced 

with a combination of formic acid and 1,8-bis(dimethylamino)naphthalene 

(Proton-Sponge) in the presence of a palladium catalyst, generated in situ from bis(dibenzylideneacetone)palladium(0)±chloroform 

complex and (R)-3-diphenylphosphino-3¢methoxy-4,4¢-biphenanthryl 

[(R)-MOP-phen] (see Section 4.4.40.14), to give 1-substituted 

chiral allylsilanes of up to 91% enantiopurity (Scheme 67). [230] Thus, reduction of (Z)-171 

gives allylsilane (S)-172 with at least 72% enantiomeric purity. The asymmetric reduction, 

under the same conditions, of allylic carbonates bearing E-configured double bonds provides 

the corresponding allylsilanes with opposite configuration to those from the Z-carbonates, 

as shown, for example, bythe preparation of (R)-173 (Scheme 67). However, the 

enantioselectivityin these cases is lower than when the Z-carbonates are used. 

76:24 

Scheme 67 1-Substituted Chiral Allylsilanes from Allylic Carbonates [230] 

OCO2Me Pd2(dba) 3 CHCl3 (cat.) 

(R)-MOP-phen 

HCO2H, Proton-Sponge 

SiEt3 90% 

Et3Si H 

(Z)-171 (S)-172 72% ee 


Pd2(dba)3 CHCl3 (cat.) 

(R)-MOP-phen 

PhMe2Si OCO2Me HCO2H, Proton-Sponge PhMe2Si 91% 

H 

(R)-173 44% ee 

(S)-Triethyl(1-methylallyl)silane [(S)-172]; Typical Procedure: [122,230] 

Under dryN 2, a mixture of Pd 2(dba) 3 ·CHCl 3 (4.7 mg, 0.0045 mmol) and (R)-MOP-phen 

(10.2 mg, 0.018 mmol) in dioxane (0.6 mL) was stirred until the soln turned orange. To 

this soln, Proton-Sponge (79 mg, 0.37 mmol), HCO 2H (31 mg, 0.69 mmol), and (Z)-171 

(73.2 mg, 0.30 mmol) were added successivelyat 0 8C. The whole mixture was kept stirring 

at 208C for 23 h. H 2O was added, and pentane extraction followed bycolumn chromatography(silica 

gel, pentane) afforded the product; yield: 45.9 mg (90%). 

4.4.40.43 Method 43: 

From Alk-2-ynylsilanes by Hydroalumination 

Monohydroalumination of alk-2-ynylsilanes followed by protonolysis of the resulting alk- 

2-enylsilanes gives Z-allylsilanes in high yield. Two different conditions have been used. 

Thus, simple alkynes, for example, 174, are reduced with 2 equivalents of diisobutylaluminum 

hydride in hexane at 708C to yield allylsilanes, for example, 29, whereas 1,3bis(trimethylsilyl)alk-1-enes, 

for example, 176, are obtained byreduction of the corresponding 

alkynes with 1.1 equivalents of diisobutylaluminum hydride in ether at 408C 

(Scheme 68). [231] The products available from both conditions are nearlyisomericallypure. 

Scheme 68 Allylsilanes by Hydroalumination of Alk-2-ynylsilanes [231] 

Bu 

Me 3Si 

( ) 4 

174 

175 

SiMe3 

SiMe 3 



1. DIBAL-H (2 equiv), hexane, 70 o C 

2. H 3O + 

85% 

1. DIBAL-H (1.1 equiv), Et2O, 40 o C 

2. H 3O + 

89% 

Bu SiMe 3 

29 (E/Z) 2:98 

( ) 4 

SiMe3 

SiMe3 176 (E/Z) 1:99 

[(Z)-Hept-2-enyl]trimethylsilane (29); Typical Procedure: [231] 

Into a dry50-mL, three-necked flask equipped with a N 2-inlet tube, reflux condenser, thermometer, 

and magnetic stirrer, and under a static N 2 atmosphere, was placed heptynylsilane 

174 (2.5 g, 15 mmol) and hexane (15 mL). To this soln was added neat DIBAL-H 

(5.5 mL, 30 mmol) at a temperature maintained at 25±30 8C bymeans of a H 2O bath for 

the duration of the addition. The soln was stirred at rt for 30 min, then heated at 708C 

for 4 h. After cooling to rt, the mixture was transferred bya double-ended needle to a vigorouslystirred 

mixture of 10% aq HCl (30 mL), ice (30 g), and pentane (15 mL). The mixture 

was stirred for 15 min, the organic phase was separated, and the aqueous phase was extracted 

with pentane (3 ” 20 mL). The combined organic extracts were washed with H 2O 

(25 mL) and brine (25 mL), and dried (MgSO 4). The solvents were removed, and the residue 

was distilled through a short Vigreux column; yield: 2.18 g (85%); bp 71±72 8C/13 Torr. 



Trimethyl[(Z)-3-(trimethylsilyl)oct-1-enyl]silane (176); Typical Procedure: [231] 

Into a dry, N 2-flushed, 50-mL, three-necked flask was placed 1,3-bis(trimethylsilyl)oct-1yne 

(175; 1.75 g, 7.0 mmol) and anhyd Et 2O (3.5 mL). To the soln was added neat DIBAL-H 

(1.4 mL, 7.6 mmol), while the temperature during the addition was maintained at 25± 

308C bymeans of a water bath. The soln was stirred at 408C for 2 h. The alkenylaluminum-containing 

mixture was cooled to rt, and was then added through a double-ended 

needle to a vigorouslystirred mixture of 10% aq HCl (15 mL), ice (15 g), and pentane 

(15 mL). The mixture was stirred for 15 min, the organic phase that formed was separated, 

and the aqueous phase was extracted with pentane (2 ” 15 mL). The combined organic extracts 

were washed successivelywith ice-cold 10% HCl (20 mL), H 2O (20 mL), and brine 

(20 mL), and then dried (MgSO 4). The solvents were removed and the residue was distilled 

through a short Vigreux column; yield: 1.59 g (89%); bp 86±87 8C/2 Torr. 

4.4.40.44 Method 44: 

From Prop-2-ynylsilanes by Hydroboration 

Although hydroalumination±protonolysis (Section 4.4.40.43) is the method of choice for 

the reduction of simple alk-2-ynylsilanes, it is not a good method for trimethyl(1-pentylprop-2-ynyl)silane 

(177). Indeed, the use of various stoichiometries of diisobutylaluminum 

hydride in a hydrocarbon or ether solvent for the hydroalumination of alkyne 

177 leads to only modest yield of the corresponding alkenylalane. However, hydroboration 

of 177 with bis(1,2-dimethylpropyl)borane, followed by protonolysis of the 

intermediate alkenylborane, gives allylsilane 178 in good yield (Scheme 69). [231] These 

conditions can also be used for the preparation of allylsilane 176 from bis(silyl)alkyne 

175 in 87% yield (GC). 

Scheme 69 Allylsilanes by Hydroboration of Prop-2-ynylsilanes [231] 

Me 3Si 

( ) 4 

177 



1. , THF, 0−25 

2 

HB 

2. AcOH 

3. H2O2 79% 

oC Trimethyl(1-pentylallyl)silane (178); Typical Procedure: [231] 

To a stirred 1.5 M soln of bis(1,2-dimethylpropyl)borane (3.4 mL, 5.1 mmol) in THF was 

added trimethyl(1-pentylprop-2-ynyl)silane (177; 0.9 g, 5.0 mmol) at 08C. The resultant 

mixture was stirred at 0±5 8C for 30 min and then at rt for an additional 30 min. The resultant 

alkenylborane was treated with glacial AcOH (0.6 mL) and was then heated at 65± 

708C for 2 h. The remaining 1,2-dimethylpropyl groups on boron were oxidized with 3 M 

NaOAc (6 mL) and 30% H 2O 2 (1.4 mL) at 35±40 8C. The mixture was maintained for 30 min 

at rt, saturated with K 2CO 3, and then extracted with Et 2O (2 ” 10 mL). The combined extracts 

were washed with brine (20 mL), dried (MgSO 4), and concentrated. The residue was 

distilled through a short Vigreux column; yield: 0.72 g (79%); bp 63±64 8C/4 Torr. 

( ) 4 

SiMe 3 

4.4.40.45 Method 45: 

From Alk-2-ynylsilanes by Catalytic Hydrogenation 

A widelyused procedure for the preparation of Z-3-substituted allylsilanes is by catalytic 

hydrogenation of the corresponding alkynylsilanes. Hydrogenation is normally run in the 

presence of a palladium catalyst such as the Lindlar catalyst, [232] but P-2 nickel (nickel boride) 

can also be used in the preparation of Z-allylsilane 180 (Scheme 70). [233] 


178

Scheme 70 An Alk-2-enylsilane by Catalytic Hydrogenation of an Alk-2-ynylsilane [233] 

SiMe 2Bu t 

H2, Ni2B (P-2 nickel) 

80% 

179 180 

SiMe2Bu t 

tert-Butyldimethyl[(Z)-1-methylbut-2-enyl]silane (180); Typical Procedure: [233] 

To a soln of Ni(OAc) 2 ·4H 2O (18 mg, 0.07 mmol) in EtOH (1 mL) under a H 2 atmosphere, a 

soln of NaBH 4 (3 mg, 0.07 mmol), dissolved in EtOH (1 mL), and ethylenediamine 

(0.01 mL, 0.14 mmol) was added. But-2-ynylsilane 179 (102 mg, 0.56 mmol) was then 

added, and the suspension was stirred for 3 h, filtered through silica gel, and the solvent 

was concentrated in vacuo. The residue was purified bycolumn chromatography(silica 

gel, pentane); this gave 180 as a colorless oil; yield: 81 mg (80%). 

4.4.40.46 Method 46: 

Formation of Exocyclic Allylsilanes by Intramolecular Reductive 

Heck Cyclization of Alk-2-ynylsilanes 

Exocyclic Z-allylsilanes have been prepared by intramolecular Heck reaction of iodobenzene 

derivatives bearing an alk-2-ynylsilane side chain in the 2-position (Scheme 71). [46] 

This reaction takes place in the presence of a catalyst system consisting of palladium(II) 

acetate (5 mol%), triphenylphosphine (10 mol%), and tetrapropylammonium bromide 

(1 equiv); sodium formate (3 equiv) is required as the hydride source. An example of this 

method is given in Scheme 71 showing the formation of allylsilanes 182 from alkynes 

181. [46] 

Scheme 71 Exocyclic Allylsilanes by Heck Cyclization [46] 

MeO 

MeO 

181 

I R1 N 



SiMe 3 

Pd(OAc) 2/Ph3P/Pr4NBr HCO2Na, DMF, 75−85 oC R1 = SO2Mes 90% 

R1 = COCF3 78% 


To a stirred suspension of HCO 2Na (3 equiv), NPr 4Br (1 equiv), Pd(OAc) 2 (5 mol%), Ph 3P 

(10 mol%), and degassed DMF, alk-2-ynylsilane 181 was added (to give a 0.05 M soln). The 

mixture was then heated to 75±858C with vigorous stirring. After completion of the reaction 

(TLC, hexane/Et 2O 3:1), the insoluble material was filtered off, and H 2O (same volume 

as DMF) and Et 2O (double the volume of DMF) were added. The phases were separated, and 

the aqueous layer was extracted with Et 2O. The combined organic phases were washed 

with H 2O and brine, dried (Na 2SO 4), and concentrated in vacuo. The residue was purified 

bychromatography. 

(1Z)-3-(Mesitylsulfonyl)-7,8-dimethoxy-1-[2-(trimethylsilyl)ethylidene]-2,3,4,5-tetrahydro-1H-3-benzazepine 

[182, R 1 =SO 2Mes]; colorless crystals; from 181 (R 1 =SO 2Mes) 

(900 mg, 1.47 mmol); yield: 644 mg (90%); mp 1168C. 

(1Z)-7,8-Dimethoxy-3-(trifluoroacetyl)-1-[2-(trimethylsilyl)ethylidene]-2,3,4,5-tetrahydro-1H-3-benzazepine 

[182, R 1 = COCF 3]; colorless crystals; from 181 (R 1 = COCF 3) (3.25 g, 

6.16 mmol); yield: 1.93 g (78%); mp 102 8C. 

MeO 

MeO 


182 

NR 1 

SiMe 3 


4.4.40.47 Method 47: 

Formation of 3-Substituted Allylsilanes by Cross Metathesis 

3-Substituted allylsilanes are available from simple trialkyl(allyl)silanes by a metathetical 

cross-coupling reaction. Three procedures have been reported, with molybdenum-, ruthenium-, 

and titanium complexes as the respective catalysts. 

4.4.40.47.1 Variation 1: 

By Molybdenum-Catalyzed Cross Metathesis 

3-Substituted allylsilanes are obtained by simple metathetical cross coupling of terminal 

alkenes with allyltrimethylsilane (1) in the presence of Schrock s molybdenum catalyst 

183 (Scheme 72). [234,235] Thus, coupling of allyltrimethylsilane with styrenes gives E-3-substituted 

allylsilanes 184 (R 1 = H, 4-Me, 2-NO 2) with excellent regio- and stereoselectivity. 

[234] More importantly, unproductive self-metathesized products are not formed. For 

simple alkyl-substituted alkenes, the metathetical coupling is still biased in favor of E-3substituted 

allylsilanes, although varying amounts of self-metathesis dimers do form in 

these cases, for example, the formation of 3-substituted allylsilanes 185 accompanied by 

ca. 33% of the self-metathesis product 186. Selectivityof alkene cross metathesis increases 

dramaticallywhen the alkenic substrates contain polar groups, for example, in 

the preparation of silane 187; verylittle isomerization is observed here despite the noted 

instability of vinylglycine esters. [235] On the other hand, acrylonitrile cross-reacts with allyltrimethylsilane 

to give trimethyl(3-cyanoprop-2-enyl)silanes with a dramatic changeover 

in E/Z selectivity[(E/Z) 1:4.7]. [234] For cross-metathesis reactions, 1,2-dimethoxyethane 

is generallythe solvent of choice; however, other solvents, such as dichloromethane can 

be used for alkenic substrates containing polar groups. [234,235] Molybdenum catalyst 183 

generallyrequires shorter reaction times and affords higher yields, although its sensitivitytowards 

atmospheric oxygen can be a disadvantage. [235] The earlier suggestion that the 

â-effect has a role to playon the selectivityof the cross-metathesis reactions has been 

questioned. [234,235] 

Scheme 72 3-Substituted Allylsilanes by Molybdenum-Catalyzed Cross Metathesis [234,235] 

F 3C 

CF 3 

O N 

Mo 

O 

F3C CF3 Ph 

R 1 

Br 

Cbz 

( ) 3 

H 

183 

CO 2Me 

NH 

97% ee 

Pr i 

+ 

Pr i 

+ 

+ 



1 

1 

SiMe3 

1 

SiMe 3 

SiMe3 

183 (cat.) 

DME 

183 (cat.) 

DME, rt, 4 h 

R1 = H 85% 

R1 = 4-Me 83% 

R1 = 2-NO2 40% 

183 (cat.) 

CH2Cl2 R 1 

184 

SiMe3 

Br 

( ) 3 SiMe3 + 

Br 

( ) 

3 

Br 

( ) 3 

185 (E/Z) 3.1:1 3:1 186 

CO2Me H 

SiMe3 

Cbz 

NH 

187 92% ee 


(E)-Trimethyl[3-(4-tolyl)allyl]silane (184,R 1 = 4-Me); Typical Procedure: [234] 

To a mixture of 4-methylstyrene (80 mg, 0.68 mmol) and allyltrimethylsilane (1; 155 mg, 

1.36 mmol) in DME (2 mL) was added molybdenum catalyst 183 (10 mg, 0.01 mmol). The 

mixture was stirred at rt for 4 h in an uncapped vial, then passed through a pad of silica 

gel and rinsed with CH 2Cl 2. The solvent was removed in vacuo, and the crude residue was 

chromatographed (silica gel containing 15% AgNO 3, hexane) to give a clear colorless oil; 

yield: 116 mg (83%). 

4.4.40.47.2 Variation 2: 

By Ruthenium-Catalyzed Cross Metathesis 

3-Substituted allylsilanes are also available by cross metathesis of terminal alkenes with 

allylsilanes in the presence of Grubbs ruthenium catalyst 189. [235±237] In particular, the reaction 

of allyltrimethylsilane (1) with carbamate 188 shows that regioselective cross coupling 

is possible (Scheme 73). [235] Furthermore, 1% divinylbenzene-crosslinked allyldimethylsilyl±polystyrene 

191 undergoes efficient ruthenium-catalyzed cross metathesis 

with polyfunctionalized molecules, such as glycosides containing terminal alkenes, to 

give functionalized allylsilanes, for example, 192. [237] 

Scheme 73 3-Substituted Allylsilanes by Ruthenium-Catalyzed Cross Metathesis [235,237] 

TrO 

AcO 

R 1 = AcO 

AcO 

H 

N O 

188 

O 

( ) 3 

191 

OAc 

+ 

SiMe2 

O 



+ 

1 

SiMe3 

R 1 

Cl 

PCy3 Ph 

Ru 

Cl 

PCy3 189 (cat.) 

CH2Cl2, reflux, 9 h 

50% 

PCy3 

Cl Ph 

Ru 

Cl 

PCy3 189 (cat.) 

TrO 

H 

N O 

O 

( )3 

190 (E/Z) 1.5:1 

6-(Trimethylsilyl)hex-4-enyl 1-[(Trityloxy)methyl]allylcarbamate (190); 


Cross metatheses were performed in a glovebox under an argon atmosphere. A soln of 

carbamate 188 (60 mg, 0.14 mmol), allyltrimethylsilane (1; 18 mg, 0.16 mmol, 1.1 equiv), 

and 5 mol% ruthenium catalyst 189 (5 mg, 0.006 mmol) in CH 2Cl 2 (2.5 mL) was refluxed for 

9 h. Separation of the mixture byflash chromatography(MTBE/petroleum ether 1:9) afforded 

carbamate 190 [(E/Z) 3:2]; yield: 37 mg (50%). 

4.4.40.47.3 Variation 3: 

By Titanium(II)-Induced Cross Metathesis 

An alternative procedure for the preparation of 3-substituted allylsilanes from simple allylsilanes 

involves treatment of the latter with in situ generated alkylidenetitanocenes 

prepared bydesulfurizative titanation of thioacetals (Scheme 74). [238] For example, triiso- 


192 

SiMe2 

SiMe 3 

R 1 


propyl(5-phenylpent-2-enyl)silane (193, R 1 = iPr; R 2 = Bn) is obtained in good yield (64%) 

along with a small amount of homoallylsilane 194 (9%) when [3,3-bis(phenylsulfanyl)propyl]benzene 

is treated with the in situ generated titanocene species 50 in the presence of 

allyltriisopropylsilane. Of note is the formation of a stereochemically enriched Z-3-substituted 

allylsilane by this protocol regardless of the substituents on the thioacetal or allylsilane. 

Scheme 74 3-Substituted Allylsilanes by Titanium(II)-Induced Cross Metathesis [238] 

SiR 1 3 

1. [TiCp2{P(OEt) 3} 2] 50, THF, 2 h 

2. R2CH2CH(SPh) 2, reflux, 6 h 

R 2 

R2 SiR1 3 + 

193 194 

R 1 R 2 Yield (%) of 193 Ratio (E/Z)of193 Ratio (193/194) R ef 

iPr Bn 64 12:88 91:9 [238] 

iPr iPr 78 11:89 84:16 [238] 

Me Bn 64 13:87 87:13 [238] 

Alk-2-enylsilanes 193; General Procedure: [238] 

To a flask charged with finelypowdered 4-Š molecular sieves (150 mg), Mg turnings 

(73 mg, 3 mmol), and [TiCp 2Cl 2] (373 mg, 1.5 mmol) was added, successively, with stirring, 

THF (3 mL), P(OEt) 3 (498 mg, 3 mmol), and the appropriate trialkyl(allyl)silane (2.5 mmol). 

After 2 h, a THF (1 mL) soln of the appropriate thioacetal (0.5 mmol) was added, and the 

mixture was refluxed for 6 h. After being cooled to rt, the mixture was diluted with pentane 

(30 mL). The insoluble materials were removed byfiltration through Celite, and the 

filtrate was concentrated. Purification bypreparative TLC gave alkenylsilane 193 along 

with the minor homoallylsilane 194 as a colorless oil; the excess trialkyl(allyl)silane was 

removed bydistillation prior to purification if necessary. 

4.4.40.48 Method 48: 

Formation of 2-Substituted Allylsilanes by the Heck Reaction 

(2-Arylallyl)trimethylsilanes can be prepared by palladium-catalyzed controlled arylation 

of allyltrimethylsilane (1) with aryl trifluoromethanesulfonates. Thus, treatment of aryl 

trifluoromethanesulfonate 195 with allyltrimethylsilane (1) in freshlydistilled acetonitrile 

under Heck coupling conditions, with palladium acetate and 1,1¢-bis(diphenylphosphino)ferrocene 

to form the catalytic system, and triethylamine or potassium carbonate 

as base, gives â-arylated allylsilane 196, accompanied bysmall amounts of terminal allylsilane 

197 in some but not all cases (Scheme 75). [239] Desilylation leading to (1-methylvinyl)arenes 

is observed when the reactions are run at higher temperatures. On the other 

hand, formation of arenes bythe reduction of aryl trifluoromethanesulfonates occurs 

mainlywith electron-deficient reactants 195 (Ar 1 = 4-AcC 6H 4, 4-NCC 6H 4, etc.); in these 

cases, use of potassium carbonate in place of triethylamine as base suppresses the reduction, 

therebyimproving the yield. Reaction times are shortened under microwave irradiation 

from 20 h to ca. 5±10 min without seriouslyaffecting the regioselectivity(Table 1). [239] 

Scheme 75 Functionalization of Allyltrimethylsilane by the Heck Reaction [239] 

Ar1OTf 195 

+ 

1 



SiMe3 

Pd(OAc)2, dppf 

MeCN, base 

Ar 1 

196 

SiMe 3 


+ 

Ar 1 

197 

SiR 1 3 

SiMe3



bTable 1 Comparison of Thermal- and Microwave-Promoted Arylation of Allyltrimethylsilane 

by the Heck Reaction [239] 

Thermal Arylation Microwave-Promoted Arylation 

Conditions Products Conditions Products 

Ar1 Ratio Combined 

(196/197) yielda Ratio Combined 

(%) 

(196/197) yieldb (%) 

Ph 608C, 20 hc 95:5 67 50Wd , 5 minc 92:8 62 

4-MeOC6H4 608C, 20 hc 97:3 42 50Wd , 5 minc 78:22e 34 

4-AcC6H4 808C, 20 hf 95:5 31 60Wd , 7 minf 100:0 48 

4-NCC6H4 808C, 20 hf 100:0 59 50Wd , 10 minf 100:0 28 

a Isolated yield. 

b GC/MS yield. 

c Et3N as base. 

d Microwave power; continuous irradiation (2450 MHz). 

e Three isomeric products detected by GC/MS. 

f K2CO3 as base. 

Preparation of (2-Arylallyl)trimethylsilanes 196 and (3-Arylallyl)trimethylsilanes 197 by 

Thermal Arylation of Allyltrimethylsilane (1); General Procedure: [239] 

A mixture of aryl trifluoromethanesulfonate 195 (2.5 mmol), Pd(OAc) 2 (16.8 mg, 

0.075 mmol), dppf (183 mg, 0.33 mmol), allyltrimethylsilane (1; 1.43 g, 12.5 mmol), Et 3N 

(0.51 g, 5 mmol) (for trifluoromethanesulfonates 195, Ar 1 = Ph, 4-MeOC 6H 4) or K 2CO 3 

(0.518 g, 3.75 mmol) (for trifluoromethanesulfonates 195, Ar 1 = 4-AcC 6H 4, 4-NCC 6H 4), and 

MeCN (10 mL) under N 2 in an oven-dried, heavy-walled, thin-neck Pyrex tube sealed with a 

Teflon stopcock was heated on an oil bath (for conditions see Table 1). After 20 h, the mixture 

was allowed to cool, diluted with H 2O, and extracted with Et 2O. The combined organic 

layers were washed with brine and concentrated in vacuo. The product was purified by 

rapid column chromatography(silica gel), followed bybulb-to-bulb distillation under reduced 

pressure, to give a clear, or, sometimes, a slightlyyellowish oil [(196/197) >95:5]. 

Preparation of (2-Arylallyl)trimethylsilanes 196 and (3-Arylallyl)trimethylsilanes 197 by 

Microwave-Promoted Arylation of Allyltrimethylsilane (1); General Procedure: [239] 

A mixture of aryl trifluoromethanesulfonate 195 (1 mmol), Pd(OAc) 2 (6.7 mg, 0.03 mmol), 

dppf (73.2 mg, 0.132 mmol), allyltrimethylsilane (1; 286 mg, 2.5 mmol), internal standard 

2,3-dimethylnaphthalene (150 mg), Et 3N (200 mg, 2 mmol) (for trifluoromethanesulfonates 

195, Ar 1 = Ph, 4-MeOC 6H 4)orK 2CO 3 (207 mg, 1.5 mmol) (for trifluoromethanesulfonates 

195,Ar 1 = 4-AcC 6H 4, 4-NCC 6H 4), and fresh MeCN (1.5 mL) was microwave-irradiated in 

an oven-dried, heavy-walled Pyrex tube (8 mL, 150 mm long) under N 2 (for conditions see 

Table 1). The tube was not filled more than one-fifth of its total volume, to allow headspace 

for pressure to build up during the microwave treatment. All couplings with microwave 

irradiation were performed without stirring. The reaction mixtures were allowed to 

cool before the tubes were carefullyopened in a fume cupboard. Small samples were removed, 

partitioned between Et 2O and H 2O, and dried (K 2CO 3), before the organic phase 

was analyzed by GC/MS. The yield was determined by a GC/MS mean value of three injections; 

calibration curves were made from pure products 196 and 2,3-dimethylnaphthalene 

as internal standard. 



4.4.40.49 Method 49: 

From [2-(Iodomethyl)allyl]trimethylsilane by Indium-Mediated 

Allylsilylation of Aldehydes or Ketones 

2-(2-Hydroxyethyl)allylsilanes 199 have been prepared bythe reaction of [2-(iodomethyl)allyl]trimethylsilane 

(198) with various aldehydes and ketones in the presence of indium 

powder at room temperature (Scheme 76). [240] Of note is the failure to prepare the corresponding 

Grignard reagent from iodide 198. [240] It is believed that an allylic indium 

sesquiiodide (R 2InI 2InIR), formed byoxidative addition of indium to the allylic halide moietyof 

198, reacts with the carbonyl compound in a cyclic transition structure. [241] 

Scheme 76 Synthesis of [2-(2-Hydroxyethyl)allyl]silanes [240] 

O 

R 1 R 2 

+ I 

SiMe3 198 



In, DMF, rt 

R1 = Ph; R2 = H 90% 

R1 = t-Bu; R2 = H 90% 

R1 = Ph; R2 = Me 71% 

1-Phenyl-3-[(trimethylsilyl)methyl]but-3-en-1-ol (199,R 1 = Ph; R 2 = H); Typical Procedure: [240] 

To a soln of allylsilane 198 (0.762 g, 3 mmol) in dryDMF (4 mL), at rt under N 2, was added 

In (In powder 99.99% from Aldrich; 0.34 g, 3 mmol), followed byPhCHO (0.21 g, 2 mmol). 

An exothermic reaction occurred. The mixture was then stirred for 1 h at rt, quenched 

with a 5% soln of Na 2HPO 4 (4 mL), and extracted with Et 2O. The organic extracts were dried 

(MgSO 4) and concentrated in vacuo. The residue was purified byflash chromatography 

(silica gel, hexane/EtOAc 9:1), giving the product as an oil; yield: 0.42 g (90%). 

4.4.40.50 Method 50: 

From [2-(Silylmethyl)allyl]lithium by a Condensation Reaction 

A varietyof 2-substituted allylsilanes can be prepared from the useful intermediate 

2-[(trimethylsilyl)methyl]allyllithium (201), which is available from trimethyl{2-[(methylselanyl)methyl]allyl}silane 

(200) bya lithium±selenium exchange reaction with butyllithium 

(Scheme 77). [242,243] For example, treatment of allyllithium 201 with alkyl halides, 

aldehydes, ketones, epoxides, or alkylideneimines provides the corresponding functionalized 

allylsilanes, for example, 202 or 203. [242,243] For the preparation of reagent 200, 

three different routes have been developed, including displacement reactions of either 

[2-(chloromethyl)allyl]trimethylsilane or the corresponding mesylate with an alkali metal 

methylselenolate, [242,243] and a less expensive technique, involving sequential treatment 

of 3-(methylselanyl)-2-[(methylselanyl)methyl]prop-1-ene with one equivalent of butyllithium 

and chlorotrimethylsilane. [242] Note, however, that alternative methods for the 

generation of 201 from [2-(halomethyl)allyl]trimethylsilane and lithium gives Wurtztype 

coupling products instead. [243,244] Furthermore, this protocol also allows synthesis of 

allylsilanes bearing different substituents on the silicon atom if analogues of 201 in 

which the trimethylsilyl group is replaced by other silicon appendages are used. [242] 


R 1 

R 2 

OH 

199 

SiMe3

Scheme 77 2-Substituted Allylsilanes from Condensation of [2-(Trialkylsilylmethyl)allyl]lithium 

with Various Electrophiles [242,243] 

200 

SiMe 3 

SeMe 



BuLi, THF 

−78 oC, 30 min 

Li 

201 

SiMe 3 

O 

73% 

Ph NMe 

90% 

202 

203 

SiMe3 

OH 

SiMe3 

Ph 

NHMe 

1-{2-[(Trimethylsilyl)methyl]allyl}cyclopent-2-en-1-ol (202); Typical Procedure: [242] 

1.6 M BuLi in hexane (1.25 mL, 2 mmol) was slowlyadded to a soln of selanyl-substituted 

silane 200 (442 mg, 2 mmol) in anhyd THF (3 mL) under argon at ±788C. The resulting yellow 

soln was stirred for 0.5 h at ±78 8C, and then quenched byslow addition of a soln of 

cyclopent-2-en-1-one in anhyd THF (2 mL). After the mixture had been stirred for 0.5 h at 

±78 8C and then treated with sat. aq NaHCO 3 (2 mL), it was allowed to warm to rt and extracted 

with Et 2O (3 ” 20 mL). The combined organic extracts were washed with H 2O 

(2 ” 5 mL) and dried (MgSO 4). The solvents were removed in vacuo to afford a crude mixture, 

which was further purified bychromatography(neutral silica gel, pentane/Et 2O 9:1); 

yield: 306 mg (73%). 

4.4.40.51 Method 51: 

From (2-Stannylallyl)silanes by Palladium(0)-Catalyzed Cross Coupling with 

Acid Chlorides or Aryl Bromides 

Functionalized allylsilanes have been prepared by a palladium(0)-catalyzed cross-coupling 

reaction of trimethyl[2-(trimethylstannyl)allyl]silane (204) with an acid chloride or 

aryl halide; for example, allylsilanes 205 and 206 were prepared from stannyl-substituted 

allylsilane 204 (Scheme 78). [132] Bis-metallic reagent 204 is available bystannylation of 3trimethylsilylallylmagnesium 

bromide generated from the corresponding bromide. [132] 

Functional-group compatibilityof this protocol is particularlynoteworthy. Similar procedures 

using transition-metal-catalyzed cross coupling of [(trimethylsilyl)methyl]vinylmetal 

(M = Mg, Zn) with vinyl or aryl halides have also been reported, [245±247] but these 

may not be suitable for the preparation of allylsilanes carrying reactive functional 

groups. [132] 



Scheme 78 2-Substituted Allylsilanes from Trimethyl[2-(trimethylstannyl)allyl]silane [132] 

Me3Sn 

204 

SiMe 3 

R 1 COCl, 1−2 mol% Pd(Bn)Cl(PPh3)2 

CHCl3, 65 o C 

R1 = Me 81% 

R1 R CHMe 89% 

= CH2CO2Me 38% 

1 = trans-CH 

R 1 Br, 1−2 mol% Pd(Bn)Cl(PPh 3) 2 

CHCl 3, 65 o C 

R1 = Ph 68% 

R1 = 4-OHCC6H4 40% 

O 

R 1 SiMe 3 

(2-Acetylallyl)trimethylsilane (205,R 1 = Me); Typical Procedure: [132] 

AcCl (160 mg, 2 mmol), CHCl 3 (2 mL), bis-metallic reagent 204 (554 mg, 2 mmol), and 

[Pd(Bn)Cl(PPh 3) 2] (30.4 mg, 0.04 mmol) were placed in a flask mounted with a CaCl 2 tube. 

The yellow soln was heated to 65 8C with stirring until blackening occurred (12 h). After 

the mixture was cooled to rt, CH 2Cl 2 (15 mL) and aq NH 4Cl (10 mL) were added. The organic 

layer was separated and the H 2O layer was washed with CH 2Cl 2 (10 mL). The combined 

extracts were dried (Na 2SO 4) and concentrated. Column chromatography(silica gel, hexane/Et 

2O 10:1) afforded allylsilane 205 (R 1 = Me); yield: 252 mg (81%). 

R 1 

205 

206 

SiMe3 

4.4.40.52 Method 52: 

From [2-(Stannylmethyl)allyl]silanes by Radical Allylsilylation with 

Alkyl Halides 

Functionalized allylsilanes are available by radical reaction of trimethyl[2-(triphenylstannylmethyl)allyl]silane 

(208) [47] or its slightly less stable tributylstannyl analogue 

211 [47,248,249] with alkyl halides. The best conditions for the reaction involve photochemical 

initiation at a temperature below 208C in benzene or 1,2-dimethoxyethane, for which 

a medium-pressure mercurylamp with Pyrex filtration is used, and the presence of 1,1¢azobisisobutyronitrile. 

Examples include the preparation of allylsilane 209 (Scheme 

79). [47] The allylsilylation reactions seem to offer a better scope with electrophilic radicals, 

for example, from bromolactone 207; nucleophilic radicals do not work well, except in a 

few specific cases, as, for example, in the preparation of allylsilane 212 (Scheme 79). [47] 

Scheme 79 2-Substituted Allylsilanes by Radical Allylsilylation [47] 

I 

Br 

+ Ph 3Sn SiMe 3 

O O 

207 208 

OMe 

OMe 

+ 

210 211 



SnBu 3 

SiMe3 

AIBN, DME, hν 

15−20 oC, 12 h 

81% 

AIBN, benzene, hν 

rt, 12 h 

72% 

O O 

209 

OMe 

SiMe3 OMe 

212 

[2-(4,4-Dimethoxybutyl)allyl]trimethylsilane (212); Typical Procedure: [47] 

A soln of 1-iodo-3,3-dimethoxypropane (210; 84.3 mg, 0.367 mmol), bis-metallic reagent 

211 (311 mg, 0.75 mmol), and AIBN (9 mg, 0.055 mmol), in drybenzene (0.9 mL), contained 

in a Pyrex test tube (1 ” 10 cm) closed by a septum, was degassed with a vigorous 


SiMe 3

stream of argon, which was passed through the soln for 6 min. The mixture was then irradiated 

for 12 h at rt (Hanovia, 140W). The solvent was removed under reduced pressure 

from the resulting cloudysoln, and flash chromatography(silica gel, EtOAc/hexane 

2.5:97.5, containing 1% Et 3N) gave the product as a colorless oil; yield: 61 mg (72%). 

4.4.40.53 Method 53: 

From [2-(Stannylmethyl)allyl]silanes by Thermal Allylsilylation with 

Acid Chlorides or Aldehydes 

Thermal reaction of trimethyl[2-(tributylstannylmethyl)allyl]silane (211) with acid chlorides 

or aldehydes provides 2-substituted allylsilanes; no catalytic activation is required 

here (Scheme 80). [250] For example, reaction of bis-metallic reagent 211 with acid chlorides 

in refluxing benzene gives functionalized allylsilane 213, whereas similar treatment with 

aldehydes in boiling toluene yields allylsilane 214. With reactive acid chlorides, for example, 

ethylmalonyl chloride, the reaction proceeds even at room temperature to give allylsilane 

213 (R 1 =CH 2CO 2Et). Bis-metallic reagent 211 can be prepared either bytreatment 

of [2-(chloromethyl)allyl]trimethylsilane with tributylstannyllithium [47,248] or byallylic 

substitution of a related sulfide or dithiocarbonate with tributyltin hydride under free 

radical conditions. [249] This protocol is compatible with the presence of a diverse range of 

functionalities, such as ester and nitro groups, in the substrates. [250] 

Scheme 80 Formation of 2-Substituted Allylsilanes by Thermal Allylsilylation [250] 

Bu 3Sn SiMe 3 

211 

R1COCl, benzene 

reflux, 1−3 h 

R1 = iPr 54% 

R1 = (CH2)2Cl 63% 

R1 = 2-furyl 69% 

R 1 CHO, toluene, reflux 

R1 = Pr 82% 

R1 = 4-EtO2CC6H4 91% 

R1 = 2-thienyl 96% 


A benzene (2 mL) soln of bis-metallic reagent 211 (833.4 mg, 2 mmol) and the appropriate 

acid chloride (2 mmol) was refluxed for 1±3 h. Sat. aq NaHCO 3 was added, and the product 

was extracted with Et 2O. The organic layer was washed with brine, dried (MgSO 4), and 

concentrated. The crude product was purified bycolumn chromatography(silica gel, hexane/Et 

2O 8:1). (The reaction of 211 with ethylmalonyl chloride was performed in benzene 

for 1 h at rt.) 

4.4.40.54 Methods 54: 

Additional Methods 



Miscellaneous other methods for the synthesis of allylsilanes are briefly discussed in this 

section; most of them were reported prior to 1990 and have not found use in organic synthesis 

to date. Also those methods which have not proven to be general are included. 

Regio- and stereoselective synthesis of 1,3-disubstituted allylsilanes are available 

from 3-substituted allylsilanes by reaction of the latter with the superbasic mixture of butyllithium 

and potassium tert-butoxide (Schlosser s base) followed byalkyl halides; only 

methyl iodide gives satisfactory results as alkylating agent. [251] 


R 1 

R 1 

O 

OH 

213 

214 

SiMe 3 

SiMe 3 




bAllylsilanes have been prepared with complete control of the C=C bond geometryby 

the Suzuki reaction involving palladium-catalyzed cross coupling of vinyl bromides with 

the organoborane 10-[(trimethylsilyl)methyl]-9-oxa-10-borabicyclo[3.3.2]decane. The airstabilityof 

the organoborane and its ease of handling makes this method particularly 

convenient. [252] 

Allylsilanes are available by nickel-catalyzed coupling of dithioacetals of ketones 

with [(trimethylsilyl)methyl]magnesium chloride. [253] 

Cross coupling of allylic sulfides and allylic ethers with silylmanganese reagents provides 

allylsilanes in good yield and with high regioselectivity; allylic halides can also be 

used as substrates in this method. [254,255] 

2-(Alkoxycarbonyl)allylsilanes are available with control of stereochemistry of the 

C=C bond by reaction of (3-ethoxyprop-2-ynyl)trimethylsilane with aldehydes, ketones, 

or acetals; this method is an alternative to the procedure described in Section 

4.4.40.10. [256,257] 

E-Allylsilanes can be accessed by the Krief±Reich reaction involving reductive elimination 

of â-hydroxy selenides; this protocol allows introduction of the allylsilane functionality 

á to the carbonyl group in cycloalkanones. [258,259] 

Cyclic allylsilanes with endocyclic alkenic bonds are available by successive treatment 

of the corresponding á-chloro ketones with [(trimethylsilyl)methyl]magnesium 

chloride and lithium powder; use of á-chloro aldehydes in this reaction leads to an equal 

mixture of E- and Z-terminallysubstituted allylsilanes. [260] 

1-Substituted allylsilanes are available by sequential addition of a nucleophile (R 1 Li) 

and tributylstannylmethyl iodide to trimethyl[(E)-2-(phenylsulfonyl)vinyl]silane followed 

by â-elimination of the resulting â-tributylstannyl sulfone. [261] 

Allylsilanes can be prepared by dehydrogenative silylation of alkenes with trialkylsilanes 

in the presence of (ç 4 -cycloocta-1,5-diene)(ç 6 -cycloocta-1,3,5-triene)ruthenium(0) as 

catalyst; a direct synthesis of ethyl (E)-4-trialkylsilylbut-2-enoate is possible by this procedure. 

[262] 

Allylsilanes have been prepared by silylation of alkenes with trialkylhalosilanes in 

the presence of a Grignard reagent and a catalytic amount of zirconocene dichloride. [263] 

The free-radical addition of trichlorosilane to â-pinene induces fragmentation to 

yield trichloro[(4-isopropylcyclohex-1-enyl)methyl]silane. [264] 

Conjugate 1,6-addition of silyllithium reagents to aromatic carbonyl compounds in 

the presence of the carbonyl protector, aluminum tris(2,6-diphenylphenoxide), provides 

allylsilanes. [265] 

1-Substituted and 1,3-disubstituted allylsilanes are available by a process involving 

organocuprate-mediated ã-coupling of silylated allylic alcohols with (methylphenylamino)tributylphosphonium 

iodide. [266] 

A synthesis of allylsilanes is based on the regio- and stereoselective hydroalumination 

of a 1-[chloromethyl(dimethyl)silyl]alk-1-yne with diisobutylaluminum hydride 

followed by treatment of the resulting alkenyl alane with 3 equivalents of methyllithium 

and then protonolysis or exposure to carbon electrophiles in the presence of a 

transition-metal catalyst. [267,268] 

Allylsilanes are available from alk-1-ynes by the generation of lithium alk-1-ynyltrialkylborates 

and treatment of the latter with (trimethylsilyl)methyl trifluoromethanesulfonate 

followed by protonolysis; this method lacks stereoselectivity. [269] Allylsilanes have 

been prepared by protonation or alkylation of lithium 1-alkynyltris[(trimethylsilyl)methyl]borates 

followed by protonolysis or treatment with aqueous sodium hydroxide and 

iodine; this method also lacks stereoselectivity. [270] 

Regio- and stereoselective [2+2] cycloaddition of dichloroketene with 5-(trimethylsilyl)cyclopentadiene, 

present in equilibrium with minor amounts of its isomers, gives a 

cyclic allylsilane, which has been used in a synthesis of a prostaglandin intermediate 

and of loganin. [271] 


Z-Vinylsilanes carrying a (tributylstannyl)methoxy substituent in the 3-position provide 

E-allylsilanes on exposure to alkyllithium by a Still±Wittig rearrangement. [272] 

Allylsilanes are available by rhodium(I)- and iridium(I)-catalyzed migration of C=C 

bonds in silylated alkenes. [273] 

Allylsilanes are available from allylic methyl ethers by reaction of the latter with photochemically 

generated dimethylsilanediyl from dodecamethylcyclohexasilanes. [274,275] 

An ingenious method is available for the transformation of á- orâ-pinene to 7-(trimethylsilyl)-á-pinene 

byan ene reaction with N-sulfinylbenzenesulfonamide, followed 

byreductive silylation. [264] 

A direct transformation of allylic acetates to allylsilanes makes use of transition-metal-catalyzed 

coupling of the former with tris(trimethylsilyl)aluminum±diethyl ether complex; 

the method is chemoselective in that acetals, esters, enones, and isolated C=C 

bonds remain unaffected, but this reaction is not always highly regio- or stereoselective. 

[276] 

Allylsilanes can be made from the crystalline ð-allylnickel halide complex available 

from the reaction between [2-(bromomethyl)allyl]trimethylsilane and bis(1,5-cyclooctadiene)nickel(0) 

with a varietyof organic halides in dimethylformamide. [277] 

Allylsilanes are available from acrylic acid or the corresponding ester carrying a trimethylsilyl 

group in the 3-position by treatment with diazoalkanes. [278] 

Applications of Product Subclass 40 in Organic Synthesis 

The widespread use of allylsilanes in organic synthesis has been covered in several reviews, 

[9±30] and no attempt will be made to duplicate these efforts here. Rather, in this section, 

the applications of some allylsilanes available by the methods described earlier (Sections 

4.4.40.1±4.4.40.53) in organic synthesis will be illustrated, so as to enable the reader 

to appreciate the importance of their specific method of preparation. In the process, a few 

examples of the major reactions of allylsilanes will be highlighted. 

4.4.40.55 Method 55: 

Protodesilylation of Allylsilanes 

Regio- and stereoselective synthesis of alkenes is possible by desilylation of an allylsilane 

bya protic acid. For this, a number of conditions are available, of which the use of the boron 

trifluoride±acetic acid complex is the preferred one; [20,21,30] it is used, for example, in 

the formation of alkene 215 from allylsilane 86B (Scheme 81). [21,147] Stereochemicallydefined 

allylsilane 86B, available from an allyl acetate by displacement with a silylcuprate 

reagent (Section 4.4.40.22.1), was used to studythe stereochemistryof some S E2¢ reactions 

of allylsilanes. In some specific cases, protodesilylation in the presence of a two-phase hydroiodic 

acid in a benzene/water mixture is found to be the onlyuseful condition, [214,279] as 

in the preparation of ester 217, an intermediate for a synthesis of ( )-methyl epijasmonate, 

from silane 216 (Scheme 81). [214] This application in synthesis took advantage of 

the method of preparation of allylsilanes described in Section 4.4.40.33. 

Scheme 81 Protodesilylation of Allylsilanes [147,214] 

Ph 

86B 

SiMe 2Ph 



BF 3 2AcOH, CH 2Cl 2 

92% 


Ph 

H 

215 


TBDPSO 

b216 

SiMe3 TBDPSO 

aq HI, benzene 

rt, 12 h 

CO2Me 

79% 

217 

CO 2Me 

trans-1-Phenyl-4-[(E)-(prop-1-enyl)]cyclohexane (215); Typical Procedure: [21,147] 

Allylsilane 86B (200 mg, 0.60 mmol) and the BF 3 ·2AcOH complex (40% BF 3 in AcOH; 

0.08 mL) were stirred in CH 2Cl 2 (5 mL) at 08C for 20 min and then at 208C for 40 min. Aq 

NaHCO 3 was added, the aqueous layer was extracted with hexane, the organic layers were 

combined and dried (MgSO 4), and the solvent was removed under reduced pressure. The 

residue was crystallized from MeOH to give alkene 215; yield: 110 mg (92%); mp 43±44 8C. 

Methyl [2-Allyl-3-(tert-butyldiphenylsiloxy)cyclopentyl]acetate (217); Typical Procedure: [214] 

To a stirred soln of ester 216 (450 mg, 0.89 mmol) in drybenzene (12 mL) was added 57% 

aq HI (0.113 ìL), and the mixture was stirred for 12 h at rt. The organic layer was washed 

with H 2O and brine, dried (Na 2SO 4), and concentrated. Preparative TLC (silica gel, pentane/ 

EtOAc 98:2) gave the product as a colorless thick oil; yield: 305 mg (79%). 

4.4.40.56 Method 56: 

Allylation of Reactive Alkyl Halides 

Allylsilanes react with reactive alkyl halides such as tert-butyl chloride, benzyl bromide, 

and so forth, in the presence of a Lewis acid to provide alkenes. [20,21,30] Examples include 

the preparation of alkene 218 (Scheme 82). [98] Allylsilane 46 was prepared bythe method 

described in Section 4.4.40.9.2. 

Scheme 82 Allylation of tert-Butyl Chloride [98] 

46 

SiMe3 

t-BuCl, TiCl4, CH2Cl2 −78 oC, 1 h 

98% 

An analogous reaction was used for the accurate determination of the degree of anti stereospecificityin 

the S E2¢ reaction of allylsilanes, as shown in Scheme 83. [170] The Z-product 

(S,Z)-219 was enantiomericallypure, but the accompanying isomer (R,E)-219 showed 

some erosion of the anti stereospecificity. In this application, practically enantiopure allylsilane 

(E)-9 was needed, preparation of which was based on the highlydiastereoselective 

aldol reaction of â-silyl enolates and stereospecific decarboxylative elimination described 

in Scheme 45 (Section 4.4.40.26). 

Scheme 83 Accurate Determination of the Degree of Stereospecificity in an S E2¢ Reaction 

of Allylsilanes [170] 

SiMe3 

(E)-9 >99.9% ee 

>99.95% E 

+ 



Cl 

TiCl 4, CH 2Cl 2 

−78 o C, 30 min 

218 

Bu t 

(S,Z)-219 >98% ee 

>99.95% Z 


+ 

60:40 (R,E)-219 80% ee 

>99.95% E

1-tert-Butyl-1-vinylcyclohexane (218); Typical Procedure: [98] 

TiCl 4 (1.04 g, 5.5 mmol) was added to CH 2Cl 2 (5 mL) and the soln was cooled to ±788C with 

stirring. This cooled soln was transferred by syringe to a stirred soln of allylsilane 46 

(910 mg, 5 mmol) and t-BuCl (0.65 mL, 6 mmol) in CH 2Cl 2, precooled to ±78 8C. After 1 h, 

the mixture was poured into sat. NaHCO 3 (25 mL), extracted with Et 2O (3 ” 50 mL), dried, 

and concentrated. The residue was purified bychromatographyor distillation; yield: 

813 mg (98%). 

4.4.40.57 Method 57: 

Radical Allylation of Alkyl Halides 

Radical allylation of alkyl halides with 2-substituted allyltris(trimethylsilyl)silanes 158, 

preparation of which is described in Section 4.4.40.38, takes place under mild conditions 

and in good yields (Scheme 84). [41] Unlike allylation reactions of allylstannanes, these reactions 

are subject to polar effects, in that, while electrophilic radicals add smoothlyto 

electron-rich acceptors, nucleophilic radicals prefer electron-poor acceptors as partners; 

this is illustrated, for example, bythe respective syntheses of alkenes 220 and 221 from 

silane 158 (Scheme 84). [41] 

Scheme 84 Allylation with Allyltris(trimethylsilyl)silanes [41] 

O 

O 

220 

O 



O 

Br 

AIBN, benzene 

reflux, 6 h 

R 1 = H 87% 

R 1 

Si(SiMe 3) 3 

158 

(t-BuO)2 

R 1 = CO 2Me 75% 

I 

221 

CO 2Me 

3-Allyldihydrofuran-2-one (220); Typical Procedure: [41] 

Allyltris(trimethylsilyl)silane (158, R 1 = H; 1.05 g, 3.63 mmol) and AIBN (0.020 g, 

0.12 mmol) were added consecutivelyto a magneticallystirred, degassed soln of 3-bromodihydrofuran-2-one 

(0.2 g, 1.21 mmol) in benzene (6 mL) under argon. The mixture was 

maintained at reflux, and additional AIBN (0.020 g, 0.12 mmol) was added everyhour. 

The reaction was monitored byTLC or GC until the starting material was consumed 

(6 h); the reaction mixture was then worked up bypassage through a short column (silica 

gel, Et 2O/pentane 2:1). After the silyl material had eluted in the first fraction, the product 

was collected; yield: 132 mg (87%). 

4.4.40.58 Method 58: 

Addition to Epoxides and Oxetanes 

Oxiranes react with allylsilanes under Lewis acid promotion to give functionalized pentenols, 

for example, pent-4-en-1-ol 222 from silane 46 (Scheme 85). [20,21,30,98] Extension of 

this methodologyfor the preparation of hexenols is possible. For example, treatment of 

prenylsilane 10, available bythe method of synthesis discussed in Section 4.4.40.1, with 

oxetane gives hex-5-en-1-ol 223. [133] 



Scheme 85 Reactions of Allylsilanes with Epoxides and Oxetanes [98,133] 

SiMe 3 

, TiCl4 

O 

80% 

46 222 

SiMe3 O 

, TiCl4 

85% 

HO 

10 223 

Intramolecular epoxy±allylsilane ring closure [20,21,30] has found use in manynatural-product 

syntheses. [28] For example, exposure of silane 224 to the boron trifluoride±diethyl 

ether complex gave ester 225, an intermediate for a synthesis of karahana ether (226) 

(Scheme 86). [87] This application in synthesis took advantage of allylsilane 36, preparation 

of which is described in Section 4.4.40.7.2, from which 224 was made bytreatment with 

m-chloroperbenzoic acid. 

Scheme 86 Synthesis of Karahana Ether [87] 

O 

224 

SiMe3 

CO2Me 

BF3 OEt2 

80% 

OH 

HO CO2Me O 

225 226 

Other examples include the transformation of cyclopentanoid allylsilane 138 (R 1 =R 2 =H; 

R 3 = Me; R 4 = Et), prepared bythe method of synthesis described in Section 4.4.40.33 

(Scheme 56), to ( )-hirsutene (229) (Scheme 87). [213] 

Scheme 87 Synthesis of ( )-Hirsutene by an Epoxy±Allylsilane Ring Closure [213] 

H 

SiMe 3 

CO 2Et 

138 R 1 = R 2 = H; R 3 = Me; R 4 = Et 



H 

H 

228 

H 

H 

227 

OH 

SiMe 3 

O 


−78 o C, 1 h 

(5,5-Dimethyl-1-vinyl-cis-octahydropentalen-2-yl)methanol (228); Typical Procedure: [213] 

A 1.8 M soln of TiCl 4 in CH 2Cl 2 (2.5 mL, 4.5 mmol), initiallycooled to ±408C, was added 

dropwise to a stirring soln of silane 227 (1.14 g, 4.28 mmol) in dryCH 2Cl 2 (25 mL) at 

±78 8C under argon. The mixture was stirred for 1 h and then quenched at the same temperature 

with sat. aq NaHCO 3 (10 mL). Extraction with Et 2O followed byremoval of solvent 

and chromatographyof the residue (silica gel, EtOAc/petroleum ether 10:90) gave 

alcohol 228 as a mixture of three diastereomers (42:50:8 byGC); yield: 600 mg (72%). 


72% 

H 

H 

229 

H

4.4.40.59 Method 59: 

Allylation of Aldehydes and Ketones 

Homoallylic alcohols are available by the reactions of allylsilanes with aldehydes or ketones 

either byprior activation of the carbonyl functionalitywith a Lewis acid or byprior 

activation of allylsilane itself with a Lewis base. In some exceptional cases, [42,43] no external 

activation is required; for an illustrative example see Scheme 5. Use of chiral Lewis 

acids [280] or chiral Lewis bases [281,282] allows asymmetric synthesis of homoallylic alcohols. 

4.4.40.59.1 Variation 1: 

By Lewis Acid Catalyzed Allylation 

Lewis acid catalyzed allylation of aldehydes and ketones with allylsilanes can provide 

homoallyl alcohols. [20,21,30] These reactions usuallyrequire stoichiometric amounts of 

Lewis acid, although a catalytic version is also possible (Scheme 4). [40] Diastereocontrol in 

the reactions of but-2-enylsilanes with aldehydes was shown in Scheme 2. Remarkably, a 

single diastereomer of dienediol 231 is obtained bythe titanium tetrachloride catalyzed 

reaction of an isomeric mixture of allylsilanes 230 with pentanal (Scheme 88). [283] Incidentally, 

the pure E,E-isomer of 230 is available bythe synthetic method described in Section 

4.4.40.21 (Scheme 36). 

Scheme 88 Stereoselective Synthesis of 6,9-Divinyltetradecane-5,10-diol [283] 

Me 3Si 

SiMe 3 

BuCHO, TiCl4 

MeNO 2, CH 2Cl 2 

69% 

230 231 

1,5-Asymmetric induction by a formal S E2 reaction of an allylsilane is also known. For example, 

transmetalation of allylsilane 232 with tin(IV) chloride, followed bytreatment of 

the resulting product with benzaldehyde provides the 1,5-anti- and 1,5-syn alkenols antiand 

syn-233 (Scheme 89). [284] The correct time lag between the tin(IV) chloride and aldehyde 

additions is critical for better yields and stereoselectivity in the synthesis of antiand 

syn-233. Allylsilane 232 was prepared bythe methodologydescribed in Section 

4.4.40.12. 

Scheme 89 1,5-Asymmetric Induction in the Reaction of a 5-Alkoxyalk-2-enylsilane [284] 

BnO 

232 

SiMe 3 



1. SnCl4, −78 oC, 2 h 

2. PhCHO, −78 oC 73% 

Bu 

OH 

OH 

OH 

OH 

+ 

BnO Ph BnO Ph 

anti-233 

73:27 

syn-233 

Sometimes, the addition of an allylsilane to an aldehyde can be combined with a pericyclic 

reaction to give polysubstituted cyclohexane derivatives, for example, the preparation 

of 234 (Scheme 90). [285] This application in synthesis took advantage of the method 

of preparation of isoprenylsilane 31 described in Section 4.4.40.7.1. 


Bu 


Scheme 90 Synthesis of Polysubstituted Cyclohexane Derivatives [285] 

SiMe 2Ph 

31 

CO2Me 20% Me2AlCl PhMe 2Si 

CO 2Me 

1. −60 oC 2. EtCHO 

3. TiCl4 

Et 

OH 

CO2Me 

234 major diastereomer 

The Lewis acid promoted allylation reactions can also be conducted intramolecularly, 

[20,21,30] for example, the formation of polycyclic compounds 236 and 238 (Scheme 

91). [112,157] While the preparation of allylsilane 235 took advantage of the Ramberg±Bäcklund 

reaction (Section 4.4.40.13), [112] allylsilane 237 was made bya straightforward silylcupration 

of allene (Section 4.4.40.24). 

Scheme 91 Lewis Acid Catalyzed Intramolecular Allylation Reactions [112,157] 

O 

O 

TBDMSO 

H 

H 

O 

CHO 

235 

237 

SiMe 3 

SiMe 2Ph 

TiCl 4, −78 o C 

TiCl 4 

61% 

70% 

O 

O 

H OH 

H 

238 

H 

TBDMSO 

Such an intramolecular allylation is also a key feature in the synthesis of fused bicyclic 

systems, for example, 240 (Scheme 92). [286] Allylsilane 239, used for this preparation, is 

available bythe method of synthesis discussed in Section 4.4.40.30. 

Scheme 92 Synthesis of Fused Bicyclic Systems [286] 

OMe 

MeO SiMe 3 

239 



OTMS , TiCl4 

H 

236 

H 

MeO 


O 

OH 

SiMe 3 

OH 

H 

OMe 

240

(5SR,6SR,9RS,10RS)-6,9-Divinyltetradecane-5,10-diol (231): [283] 

A three-necked flask equipped with a thermometer, septum cap, magnetic stirring bar, 

and argon outlet was charged with anhyd CH 2Cl 2 (23 mL) and anhyd MeNO 2 (3.2 mL). The 

soln was cooled to ±60 8C and TiCl 4 (1.7 mL, 15.5 mmol) was added, followed byBuCHO 

(15 mmol) in CH 2Cl 2 (2 mL). After 15 min of stirring at ±708C, the soln was cooled to 

±90 8C, and bis(allylsilane) 230 (7.62 g, 30 mmol) in CH 2Cl 2 (3 mL) was added over 10 min. 

The resulting soln was stirred at ±908C for 1 h and at ±608C for 4 h, after which the reaction 

was complete, as indicated byTLC analysis. The mixture was quenched byaddition of 

sat. aq NH 4Cl (40 mL) and extracted with CH 2Cl 2 (3 ” 25 mL). The extracts were washed until 

neutral, dried (MgSO 4), and concentrated under vacuum. The residue was purified by 

column chromatography(silica gel, pentane, pentane/Et 2O 4:1); yield: 1.47 g (69%); mp 

878C. 

4.4.40.59.2 Variation 2: 

By Lewis Base Promoted Allylation 

Homoallyl alcohols are also available by allylation of aldehydes with allylsilanes in the 

presence of a Lewis base, for example, the fluoride ion. [20±22,30] These reactions are sometimes 

regioselective, as, for example, the preparation of fluorinated homoallylic alcohol 

241 (Scheme 93). [62] This application of allylsilane 19, prepared bythe electroreductive 

synthesis described in Section 4.4.40.4, demonstrates how easily a difluoromethylene 

moietycan be introduced into an organic molecule. 

Scheme 93 Use of (Difluoroallyl)silanes as Difluoromethyl Anion Equivalents [62] 

Me3Si 

EtO 

19 

F 

F 

Ph 

EtCHO, TBAF, THF 

51% 

Et 

OH 

F 

Aldehydes with a built-in allylsilane functionality can undergo fluoride ion induced cyclizations, 

for example, the formation of 3-methylenecyclohexanols 243A and 243B [(243A/ 

243B) 18:82] (Scheme 94). [66,67] Interestingly, the diastereoselectivity of this reaction can 

be reversed [(243A/243B) 85:15] byuse of the boron trifluoride±diethyl ether complex as 

the Lewis acid catalyst. Allylsilane 242 is available from 24 (n = 1), preparation of which is 

described in Section 4.4.40.5.1. 

Scheme 94 Stereodivergent Synthesis of 3-Methylenecyclohexanols [66,67] 

H 

H 

242 

SiMe 3 

CHO 



A: TBAF, THF 

B: BF3 OEt2, CH2Cl2 

A: (243A/243B) 18:82 

B: (243A/243B) 85:15 

EtO 

241 

H 

F 

Ph 

H 

243A 

OH 

+ 

H 

H 

243B 

Lewis base promoted intramolecular allylation is also possible, for example, the preparation 

of benzopentalene derivative 245 (Scheme 95). [47] Allylsilane 244 was prepared bythe 

method described in Section 4.4.40.52. 


OH 


Scheme 95 Synthesis of a Benzopentalene Derivative [47] 

O 

244 

SiMe3 

TBAF, THF 

74% 

In addition to the fluoride ion, other Lewis bases have also been used in the allylation of 

aldehydes. [281,282,287,288] For example, dimethylformamide was used as a Lewis basic ligand 

in the stereoselective preparation of the syn- and anti-homoallylic alcohols syn- and anti- 

246 from Z- and E-allyltrichlorosilanes (Z)- and (E)-59, respectively(Scheme 96). [287] While 

the E-but-2-enylsilane (E)-59 is available bya method described in Section 4.4.40.16, the Zbut-2-enylsilane 

(Z)-59 is prepared by hydrosilylation of buta-1,3-diene (Section 4.4.40.14). 

Scheme 96 Allylation of Benzaldehyde [287] 

SiCl 3 

PhCHO, DMF, 0 o C, 2 h 

82% 

HO 

245 

(Z)-59 (E/Z) 99 syn-246 (syn/anti) >99:

Scheme 97 Synthesis of Homoallylic Ethers [79,237] 

Cl 

SiMe 3 

28 R 1 = H; X = Cl 

+ 

192 R 1 = Bn 

Ph OMe 

SiMe 2 

OMe 

Bn 

+ 

BF 3 OEt 2 

85% 

OEt 

OEt 

Ph 

Cl 

OMe 

247 major isomer 


−78 o C, 2 h 

Intramolecular cyclization of allylsilanes with an acetal function can provide a variety of 

heterocyclic compounds. For example, tetrahydropyran 250 is prepared in 92.8% ee from 

hydroxy-substituted chiral allylsilane (S,E)-249 (93.2% ee) (Scheme 98). [289] Here, silane 

(S,E)-249 was prepared by the intramolecular silylsilylation protocol described in Section 

4.4.40.20. In this case, intramolecular cyclization proceeds with nearly complete chirality 

transfer. 

Scheme 98 Asymmetric Synthesis of Tetrahydropyrans [289] 

HO 

( ) 3 

SiMe2Ph 

Bu 

(S,E)-249 93.2% ee 

iPrCHO 

TMSOTf 

−78 oC 99% 

O 

Pr i 

OTMS 

SiMe 2Ph 

Bu 

Bn 

248 

OEt 

O Pr i 

Bu 

250 92.8% ee 

2-Benzyl-1-methylbut-3-enyl Ethyl Ether (248): [237,311] 

To polystyrene-supported allylsilane 192 (500 mg) in CH 2Cl 2 (20 mL) was added 1,1diethoxyethane 

(153 mg, 1.3 mmol) and TiCl 4 (250 mg, 1.3 mmol) at ±788C. After 2 h a 

sat. aq NaHCO 3 was added. The organic phase was separated and the NaHCO 3-phase was 

extracted (3 ”) with CH 2Cl 2. Flash chromatography(MTBE-light petroleum ether [bp 40± 

608C] 1:6 to 1:3) of the residue gave the product; yield: 51 mg (0.50 mmol ·g ±1 of 192). 

4.4.40.61 Method 61: 

Acylation with Acid Chloride 

Lewis acid mediated reactions of allylsilanes with acid chlorides provide â,ã-unsaturated 

ketones, for example, the synthesis of artemesia ketone (251) (Scheme 99). [52] This synthetic 

application took advantage of the preparation method of allylsilane 10 described 

in Section 4.4.40.1. 

Scheme 99 Synthesis of Artemesia Ketone [52] 

O 

Cl 

+ 



10 

SiMe 3 

AlCl3, CH2Cl2, −60 oC 90% 

3,3,6-Trimethylhepta-1,5-dien-4-one (Artemesia Ketone, 251): [52] 

A mixture of 3-methylbut-2-enoyl chloride (11.85 g, 0.1 mol) and AlCl 3 (13.35 g, 0.1 mol) in 

CH 2Cl 2 (50 mL) was added dropwise over 45 min to a stirring soln of but-2-enylsilane 10 

(15.65 g, 0.11 mol) in CH 2Cl 2 (100 mL), previouslycooled to ±608C. The mixture was kept 

at this temperature for 10 min after the final addition, and then poured slowlyonto a mix- 


O 

251 


ture of crushed ice and NH 4Cl. The organic layer was washed with brine, dried (MgSO 4), 

and concentrated in vacuo; yield: 13.68 g (90%); bp 878C/200 Torr. 

4.4.40.62 Method 62: 

Reaction with Iminium Ions 

Homoallyl amines are available by the treatment of allylsilanes with in situ generated 

iminium ions; the intramolecular variant of this process can provide a varietyof heterocyclic 

ring systems. [21,30] An example of allylsilane±iminium ion ring closure for the synthesis 

of 2,6-disubstituted tetrahydropyridines 253 is shown in Scheme 100. [290] Allylsilane 

252, used in this work, was derived from an á-amino acid byutilizing the method 

described in Section 4.4.40.5.2 in one of the steps. 

Scheme 100 Synthesis of 2,6-Disubstituted Tetrahydropyridines [290] 

R 1 

NHBoc 

252 

SiMe 3 

+ Pr i CHO 


R 1 = Me 45% 

R 1 = iBu 51% 

R N 

H 

1 Pri Another example of allylsilane±iminium ion cyclization route is that to the tricyclic nucleus 

255 of marine alkaloid sarin A (Scheme 101). [151] Allylsilane 254, which proved difficult 

to synthesize bya Wittig route (Section 4.4.40.9), was successfullymade bythe methodologydescribed 

in Section 4.4.40.22.1. 

Scheme 101 An Intramolecular Allylsilane±N-Tosyliminium Ion Cyclization [151] 

BnN 

O OH 

H Bn H Bn 

N 

N 

TsN 

H 

254 

H 



SiMe3 

2-Isopropyl-6-methyl-1,2,3,6-tetrahydropyridine (253,R 1 = Me); Typical Procedure: [290] 

Under argon, iPrCHO (42 mg, 0.57 mmol) was dissolved in dryCH 2Cl 2 (0.5 mL), and the 

soln was cooled to 0 8C. TiCl 4 (108 mg, 0.57 mmol) was added bysyringe, and the bright 

yellow mixture was warmed to rt. Allylsilane 252 (R 1 = Me) (150 mg, 0.58 mmol) in 

CH 2Cl 2 (0.25 mL) was added. After stirring for 3 min, the mixture was cooled to 08C and 

sat. aq NH 4Cl (0.5 mL) was added bysyringe, followed byEt 2O (2 mL). The ethereal layer 

was separated, washed with brine, and dried (Na 2SO 4). Tetrahydropyridine 253 (R 1 = Me) 

was isolated bycolumn chromatography(silica gel); yield: 37 mg (45%). 

4.4.40.63 Method 63: 

Epoxidation and Ring Opening 

Epoxidation of allylsilanes and subsequent desilylative opening can provide allylic alcohols 

with synthetically useful levels of stereoselectivity. [21] Acyclic allylsilanes, in particular, 

react with reasonable chiralitytransfer. Thus, allylsilane 256, prepared bythe method 

described in Section 4.4.40.7.1, gives a mixture of allyl alcohols (S,E)- and (R,Z)-257 

(Scheme 102). [291] 

H 

H 

253 

SiMe3 

FeCl 3 


61% 

H 

TsN 

H 

255 

NBn 

H

Scheme 102 Synthesis of Enantiomerically Enriched Allyl Alcohols [291] 

Ph 

Me3Si 

H 

256 81% ee 

1. MCPBA, NaHCO3, CH2Cl2 2. AcOH, MeOH 

98% 

Ph 

H 

OH 

(S,E)-257 73% ee 

+ 

81:19 

Ph H 

OH 

(R,Z)-257 72% ee 

Allylsilanes bearing an acid, ester, or amide functionality in a strategic position may follow 

a different reaction course to give lactones; [204,292] an example is the preparation of 

lactone 258, an intermediate for a synthesis of parasorbic acid (259) (Scheme 103). [204] 

This application in synthesis took advantage of the S-enantiomer of allylsilane 132, prepared 

bythe method of synthesis described in Section 4.4.40.31.3. 

Scheme 103 Synthesis of Parasorbic Acid [204] 

Me2N 

O 

SiMe3 

MCPBA, CH2Cl2 

−20 o C 

(S)-132 258 major diastereomer 

O 

O 

SiMe3 

OH 

BF3 OEt2 

99% 

(S,E)- and (R,Z)-4-Phenylbut-3-en-2-ol [(S,E)- and (R,Z)-257]: [21,291] 

Trimethyl[(R,E)-1-phenylbut-2-enyl]silane (256; 81% ee; 0.622 g, 3.04 mmol) in CH 2Cl 2 

(10 mL) was mixed with NaHCO 3 (0.252 g, 2.99 mmol) and MCPBA (0.72 g, 80%, 

3.34 mmol) in CH 2Cl 2 (15 mL) with stirring at ±788C. Stirring continued at 08C for 1 h, before 

the solvent was removed in vacuo. MeOH (12 mL) and AcOH (2 mL) were added and 

the soln was washed with 20% NaOH (4 ” 50 mL) and H 2O. The organic layer was dried 

(MgSO 4) and concentrated, and the residue was purified byTLC (silica gel, CHCl 3), to give 

a mixture of allylic alcohols (S,E)-257 and (R,Z)-257 (S,E/R,Z 81:19); yield: 0.441 g (98%). 

4.4.40.64 Method 64: 

Aziridination and Ring Opening 

â,ã-Unsaturated amino acids, noted for their pharmacological properties, can be made by 

aziridination of allylsilanes followed by spontaneous desilylative ring opening. For example, 

addition of (ethoxycarbonyl)nitrene, generated from ethyl [(4-nitrophenyl)sulfonyl]oxycarbamate, 

to allylsilane 260 gives â,ã-unsaturated á-amino ester derivative 261 

(Scheme 104). [90] However, ester 262 under similar conditions gives a mixture of 263 and 

264 (263/264 1.6:1); protodesilylation of vinylsilane 264 yields alkene 263, therebyimproving 

the overall yield in this reaction. [90] This application took advantage of the method 

of synthesis of allylsilanes described in Section 4.4.40.7.3. 

Scheme 104 Preparation of â,ã-Unsaturated á-Amino Esters [90] 

Ph 

Me3Si CO2Et 260 



4-O2NC6H4SO3NHCO2Et CaO, CH2Cl2 Ph 

CO2Et 

HN CO2Et 


261 

O 

O 

259 


4-O2NC6H4SO3NHCO2Et CO2Me CaO, CH2Cl2, rt, 20 h 

SiMe3 

262 

66% 

CO2Me CO2Et N 

H 

263 

+ 

Me3Si 

1.6:1 264 

CO2Me CO2Et N 

H 

â,ã-Unsaturated á-Amino Ester Derivatives 263 and 264; Typical Procedure: [90] 

To a stirred soln of allylsilane 262 (540 mg, 2.8 mmol) in CH 2Cl 2 (2 mL) at rt, CaO and 4- 

O 2NC 6H 4SO 3NHCO 2Et were added portionwise [molar ratio (substrate/4-O 2NC 6H 4SO 3- 

NHCO 2Et/CaO) 1:5:5]. The mixture was stirred for 20 h, CH 2Cl 2 (10 mL) and hexane 

(100 mL) was added. After filtration, the liquid phase was concentrated in vacuo. The 

products were purified byflash chromatography(silica gel, EtOAc/hexane 2:8); á-amino 

esters 263 and 264 were collected separately; yield of 263: 260 mg (41%); yield of 264: 

210 mg (25%). 

4.4.40.65 Method 65: 

Dihydroxylation of Allylsilanes 

Osmium tetroxide reacts with allylsilanes to give silylated 1,2-diols which are readily convertible 

to allylic alcohols in various ways. [21] Thus, allylsilane 135 was converted into allylic 

alcohol 265, a keyintermediate for a synthesis of ( )-shikimic acid (266) (Scheme 

105). [209] This application demonstrates the use of allylsilane 135, as well as its method 

of preparation, as described in Section 4.4.40.32. 

Scheme 105 Synthesis of ( )-Shikimic Acid [209] 

OAc 

SiMe 3 

135 

CO 2Me 



1. OsO4 2. TsOH 

94% 

OH 

HO CO2Me 

HO 

CO2H 265 

HO 

OH 

( + 

−)-266 

Chiral allyl alcohols with moderate enantiopurity are also available by Sharpless asymmetric 

dihydroxylation of allylsilanes, followed by Peterson-type elimination. [293] On the 

other hand, Sharpless dihydroxylation of allylsilane 121 (preparation in Section 

4.4.40.31.1) in the presence of dihydroquinidine 4-chlorobenzoate as catalyst gives ã-lactones 

(±)-267A and (+)-267B with some control of diastereoselectivity(Scheme 106). [198] 

The aim of this work was to investigate the possibilityof increasing the diastereoselectivity 

in dihydroxylation of allylsilanes, a reaction known to be less selective than epoxidation 

and related reactions. 


Scheme 106 Diastereoselective Synthesis of â,ã-Disubstituted ã-Butyrolactones [198] 

Et 

CO2Me 

SiMe2Ph 121 

OsO4, K3[Fe(CN)6], K2CO3 

dihydroquinidine 4-chlorobenzoate (cat.) 

t-BuOH, H2O, rt, 18 h 

PhMe2Si 

Et 

HO 

O 

(−)-267A 

O 

+ 

87:13 

PhMe 2Si 

Et 

HO 

O 

(+)-267B 

(±)-(4R,5S)-4-(Dimethylphenylsilyl)-5-[(1R)-1-hydroxypropyl]dihydrofuran-2-one [(±)-267A] 

and (+)-(4R,5R)-4-(Dimethylphenylsilyl)-5-[(1S)-1-hydroxypropyl]dihydrofuran-2-one 

[(+)-267B]; Typical Procedure: [198] 

A 2% w/v soln of OsO 4 in t-BuOH (60 ìl, 4.53 ìmol) was added to a stirred soln of alk-2-enylsilane 

121 (100 mg, 0.36 mmol), K 3[Fe(CN) 6] (358 mg, 1.09 mmol), dihydroquinidine 4-chlorobenzoate 

(84 mg, 0.181 mmol), and K 2CO 3 (150 mg, 1.09 mmol) in t-BuOH/H 2O (1:1; 

5.5 mL), and the mixture was stirred at rt for 18 h. Na 2S 2O 5 (ca. 500 mg) was then added, 

and the mixture was stirred at rt for 1 h before being concentrated to dryness. The solid 

residue was partitioned between EtOAc (10 mL) and 1 M aq HCl (10 mL); the organic phase 

was separated, dried (MgSO 4), and concentrated to give a mixture of lactones (±)-267A and 

(+)-267B [(±)-267A/(+)-267B 87:13]. This mixture was separated byflash chromatography; 

lactone (+)-267B eluted first (EtOAc/petrol 20:80), yielding a crystalline solid; yield: 11 mg 

(11%); mp 62±64 8C. Further elution (EtOAc/petrol 33:77) gave lactone (±)-267A as a colorless 

oil; yield: 65 mg (65%). 

4.4.40.66 Method 66: 

Conjugate Addition to á,â-Unsaturated Carbonyl Compounds 

The addition reactions of allylsilanes to á,â-unsaturated ketones (Sakurai reaction) and 

the corresponding intramolecular version have found widespread use in synthesis. [20,21,30] 

For an example of the intermolecular reaction, see Scheme 1. An additional example is 

presented in Scheme 107, involving the reaction of cyclohex-2-enone with (E)-but-2-enylmethyldiphenylsilane 

(15, R 1 = Me; R 2 = Ph), prepared bythe synthetic method described 

in Section 4.4.40.2. The resulting erythro-selective Sakurai reaction gave cyclic ketone 268 

as the major diastereomer, which was elaborated to epijuvabione (269). [294] 

Scheme 107 Synthesis of Epijuvabione [294] 

O 

TiCl 4 

SiMePh 2 

15 R 1 = Me; R 2 = Ph 



O 

H 

268 

MeO2C 

The preparation of a precursor for ( )-tricyclohexaprenol (Scheme 108) also entails an intermolecular 

Sakurai reaction, and made use of allylsilane 270, prepared bythe protocol 

discussed in Section 4.4.40.23. [295] 


H 

269 

O 

O 


Scheme 108 Synthesis of a Precursor for ( )-Tricyclohexaprenol [295] 

O 

+ 

SiMe 3 

270 

OTBDPS 

H 

O 

TiCl4, CH2Cl2 

54% 

OTBDPS 

In some cases, silylcyclopentanes are obtained as minor byproducts of the Sakurai reaction, 

such reactions becoming competitive with bulkysilyl appendages (see Section 

4.4.40.69). 

An intramolecular Sakurai reaction involving addition of an allylsilane function to 

an in situ generated enedione was used for the synthesis of pyridoxatin (272) from silane 

271 (Scheme 109). [296] This application took advantage of the method of synthesis of allylsilanes 

described in Section 4.4.40.9. 

Scheme 109 Allylsilane-Mediated Synthesis of Pyridoxatin [296] 

Me 3Si 

OH 

N 

H 

OH 

O 

271 

Me2AlCl 35% 

Diastereoselective synthesis of carbocyclic rings is also possible by intramolecular reaction 

of allylsilanes with unsaturated carbonyl compounds. For example, allylsilane 273, 

prepared from 146 (R 1 = H; n = 2) bya Knoevenagel condensation reaction, gives enantiomericallypure 

trans-1,2-disubstituted cyclopentane 274 as the major product on Lewis 

acid catalyzed ring closure (Scheme 110). [297] This application took advantage of the method 

of synthesis of allylsilanes described in Section 4.4.40.36. 

Me 3Si 

O 

N 

H 

O 

Scheme 110 Synthesis of Enantiomerically Pure trans-1,2-Disubstituted Cyclopentanes [297] 

Me3Si 

MeO2C 

273 

O 

N 

Pr i 

O 



O 

Me2AlCl 

61% 

MeO 2C N O 

8a-Allyl-cis-octahydronaphthalen-2-one (3); Typical Procedure: [35] 

TiCl 4 (379 mg, 2 mmol) was added dropwise to a soln of 4,4a,5,6,7,8-hexahydronaphthalen-2-one 

(300 mg, 2 mmol) in CH 2Cl 2 (3 mL). After 5 min, the soln was cooled to ±788C, 

and allyltrimethylsilane (1; 319 mg, 2.8 mmol) was added dropwise. The mixture was 

O 

274 

Pri H 


H 

O 

OH 

N 

H 

O 

272

stirred for 18 h at ±78 8C, and 5 h at ±308C. H 2O was added to the mixture, and the organic 

product was then extracted thoroughlywith Et 2O. The combined organic extracts were 

washed with H 2O, dried, and concentrated. Distillation of the residue gave the product; 

yield: 326 mg (85%); bp 1208C/5 Torr. 

4.4.40.67 Method 67: 

Palladium(0)-Catalyzed [3+2] Cycloaddition 

In the presence of a palladium(0) catalyst, [2-(acetoxymethyl)allyl]trimethylsilane (34) 

serves as a useful annulating reagent for alkenes bearing electron-withdrawing groups; 

examples of this are the syntheses of ester 275 and ketone 276 (Scheme 111). [68,298] For cyclohex-2-enones, 

additional activation of the alkenic moietyis needed for efficient reaction, 

as in, for example, the formation of polycyclic 278. [299] One of the most convenient 

procedures for the preparation of allylsilane 34 is illustrated in Section 4.4.40.7.1. 

Scheme 111 Palladium(0)-Catalyzed [3 +2] Cycloaddition [68,298,299] 

Me 3Si OAc 

34 

H2C CHCO2Me, Pd(0) catalyst 

H 

O 

68% 

, Pd(0) catalyst 

O 

52% 

71% 

CO 2Me 

Pd(OAc)2, P(OEt) 3 

THF, reflux, 22 h 

277 

H 

O 

CO2Me 275 

276 

O 

CO2Me 

In addition to the [3 +2] cycloadditions discussed above, [3+4]- and [3+6]-cycloaddition 

reactions are also possible with allylsilane 34. [300±302] 

Silane 279, another conjunctive reagent, carrying a phenylsulfanyl group, also allows 

regioselective cycloaddition reactions, no catalyst poisoning being observed here 

(Scheme 112). [175] This application took advantage of the method of synthesis of allylsilanes 

described in Section 4.4.40.28. 

Scheme 112 Regioselective Synthesis of Methylenecyclopentanes [175] 

PhS 

Me3Si OCO 2Me 

279 



+ 

Ph 

CO2Me 

CO 2Me 

Pd(0) catalyst 

85% 

H 

278 

PhS 


CO2Me 

Ph CO2Me for references see p 920

Methyl (3aRS,5aRS,8SR,9RS,9aRS,9bSR)-8,9a-Dimethyl-9-(3-methylbut-3-enyl)-2-methylene-4-oxododecahydro-3aH-benz[e]indene-3a-carboxylate 

(278); Typical Procedure: [299] 

A soln of ester 277 (200 mg, 0.65 mmol), Pd(OAc) 2 (31 mg, 0.14 mmol), (EtO) 3P (115 ìL, 

0.71 mmol), and allylsilane 34 (225 mg, 1.21 mmol) in THF (3 mL) was refluxed for 22 h. 

The resulting soln was cooled, concentrated, and purified bycolumn chromatography 

(silica gel, pentane/Et 2O 9:1), to furnish a yellow oil, which solidified upon standing. 

Recrystallization from hexane gave the product as a white solid; yield 168 mg (71%); mp 

87±88 8C. 

4.4.40.68 Method 68: 

[3+4] Allyl Cation Cycloaddition 

[3+4] Allyl cation cycloaddition of allylsilane 281, prepared from silane 49 (R 1 = Me) via 

allyl alcohol 280, with cyclopentadiene gives diene 282 as the major product (Scheme 

113). [101] The intramolecular variant of this reaction provides a route to hydroazulenes, 

for example, cis- and trans-284. [105] These synthetic applications illustrate the usefulness 

of the preparation methods described in Section 4.4.40.10. 

Scheme 113 Synthesis of Bridged Methylenecyclohexanes and Hydroazulenes by [3+4] 

Allyl Cation Cycloaddition [101,105] 

SiMe 3 

OH 

280 

SiMe3 

OH 

283 



TFAA, iPr 2NEt, CH 2Cl 2 

Tf2O, 2,6-lut, CH2Cl2 

−78 oC, 1 h 

55−65% 

SiMe 3 

, ZnCl 2 

MeCN, 0 

F3COCO 281 282 

oC, 6 h 

60% 

2,2,4-Trimethyl-3-methylenebicyclo[3.2.1]oct-6-ene (282): [101,303] 

Under N 2, a soln of silane 280 (1.5 g, 8 mmol) in dryCH 2Cl 2 (6 mL) was added dropwise to a 

vigorouslystirred mixture of TFAA (1.25 mL, 8.8 mmol) and iPr 2NEt (1.5 mL, 8.8 mmol) in 

dryCH 2Cl 2 (15 mL) at ±60 to ±708C. The resulting yellow soln was stirred for a further 3 h, 

allowed to reach ±308C, and then diluted with precooled (±208C) pentane (ca. 60 mL). This 

soln was eluted with precooled (±208C) pentane through a short column of basic alumina 

(activitygrade 1), maintained at ±60 to ±408C bymeans of a cooling jacket. The solvent 

was carefullyremoved in vacuo from the combined filtrate, which was kept at a temperature 

below 08C, and maintained at a volume of ca. 50 to 70 mL, bysimultaneous, gradual 

replacement of the removed CH 2Cl 2/pentane bydryMeCN. Aliquots of this MeCN soln 

containing trifluoroacetate 281 were immediatelyused, without further purification, 

for the next step (decomposition within min after complete evaporation; gradual deterioration 

in soln at 08C); IR (CHCl 3): í 1778 (C=O), 1258, 1170, 849 cm ±1 . 

Under N 2, cyclopentadiene (from the dimer; 0.39 mL, 4.7 mmol) was added at 08Ctoa 

suspension of dryZnCl 2 (0.8 g, 5.8 mmol) in dryMeCN (10 mL). A soln of trifluoroacetate 

281 (ca. 2.9 mmol), prepared as described above, in dryMeCN was slowlyadded under vigorous 

stirring, and stirring was continued for another 6 h at 08C. The resulting orange to 

dark-red mixture was extracted with pentane (2 ” 25 mL), the combined extracts were 


H 

H 

284

shaken with some solid K 2CO 3 and filtered, and the filtrate was concentrated in vacuo at 

below 208C. The residue was further distilled (Kugelrohr; 60±80 8C/25 Torr) giving bicyclooctene 

282 contaminated with 14% [(2Z)-2-isopropenylbut-2-enyl]trimethylsilane; yield: 

280 mg (ca. 60%). (The use of an equimolar amount of cyclopentadiene for the cycloaddition 

reaction is advisable, as excess cyclopentadiene tends to form the dimer, which 

causes trouble during workup of the reaction mixture.) 

cis- and trans-4-Methylene-1,2,3,3a,4,5,6,8a-octahydroazulene (284): [105] 

A flame-dried 150-mL flask under argon was charged with trienylsilane 283 (175 mg, 

0.73 mmol) and CH 2Cl 2 (105 mL). The soln was cooled to ±788C, and 2,6-lutidine (202 mg, 

1.89 mmol) followed byTf 2O (300 mg, 1.06 mmol) were added. After 1 h, the clear soln was 

quenched at ±788C with sat. aq NaHCO 3, allowed to warm to rt, and worked up byextraction 

with CH 2Cl 2. The organic layer was washed with sat. aq NaHCO 3 (150 mL), sat. aq 

CuSO 4 (3 ” 75 mL or until GC analysis shows absence of lutidine), and brine (100 mL) and 

dried (K 2CO 3). Concentration at atmospheric pressure, followed byKugelrohr distillation 

(±788C) or flash chromatography(Al 2O 3/pentane) afforded a pleasant-smelling colorless 

oil consisting of cis- and trans-hydroazulenes 284; yield 59±70 mg (55±65%). 

4.4.40.69 Method 69: 

Hydroxycyclopentanes from [3+2] Annulation with á-Enones 

Allylsilanes with bulky ligands on silicon, such as allyl(tert-butyl)diphenylsilane (12, 

R 1 = t-Bu; R 2 = Ph), are useful reagents for stereocontrolled construction of various ring systems 

byLewis acid promoted formal [3+2]-cycloaddition reactions with á-enones, for example, 

the formation of silane 285 (Scheme 114). [44,45] Tamao±Fleming oxidation of silane 

285 replaces the silyl group with a hydroxy group, with retention of configuration, as, for 

example, in the formation of cyclic alcohol 286. [45,55] The synthesis of allyl(tert-butyl)diphenylsilane 

(12, R 1 = t-Bu; R 2 = Ph), used for this transformation, is described in Section 

4.4.40.1.1. 

Scheme 114 Synthesis of Hydroxycyclopentanes [45,55] 

Ac 



12 R 

TiCl4, CH2Cl2 1 = t-Bu; R2 = Ph 

69% 

SiBu t Ph 2 

Ac 

H 

285 

SiBu t Ph 2 

Tamao−Fleming oxidation 

82% 

3a-Acetyl-2-(tert-butyldiphenylsilyl)octahydroindene (285); Typical Procedure: [55] 

A soln of 1-acetylcyclohexene (500 mg, 4.03 mmol) in CH 2Cl 2 (2 mL) was added to a soln of 

TiCl 4 (840 mg, 4.43 mmol) in CH 2Cl 2 (5 mL) at ±208C; a yellow suspension formed. After 

the mixture had cooled to ±788C, a soln of allyl(tert-butyl)diphenylsilane (12, R 1 = t-Bu; 

R 2 = Ph; 1.69 g, 6.04 mmol) in CH 2Cl 2 (6 mL) was added, and the mixture was warmed slowlyto 

08C (the color changed to reddish-violet) and stirred vigorouslyfor 19 h at this temperature. 

Another portion of allyl(tert-butyl)diphenylsilane (12, R 1 = t-Bu; R 2 = Ph; 1.13 g, 

4.03 mmol) in CH 2Cl 2 (6 mL) was added, and the mixture was stirred for an additional 

24 h, after which it was poured into aq NH 4Cl. The organic layer was separated, the aque- 


Ac 

H 

286 

OH 


ous layer was extracted with CH 2Cl 2 (3 ”), and the combined organic layers were dried 

(Na 2SO 4). The solvent was removed under reduced pressure and the residue was purified 

byflash chromatography(silica gel, pentane/Et 2O 20:1), to afford the product as colorless 

crystals; yield 1.12 g (69%); mp 115±1168C. 

4.4.40.70 Method 70: 

Tetrahydrofurans by [3+2] Annulation with Aldehydes and Ketones 

Lewis acid promoted [3+2] annulation of allylsilanes with aldehydes and ketones can provide 

substituted tetrahydrofurans. [202,304±307] Thus, chiral (E)-but-2-enylsilane 287, (preparation 

method in Section 4.4.40.31.2) has been used in a synthesis of optically pure cis-2,5substituted 

tetrahydrofuran 288 (Scheme 115). [202] A similar reaction involving allyl(tertbutyl)diphenylsilane 

(12,R 1 = t-Bu; R 2 = Ph) and á-keto ester 289 gives trisubstituted tetrahydrofuran 

290 with high stereoselectivity. [304] 

Scheme 115 Synthesis of Substituted Tetrahydrofurans [202,304] 

CO2Me 

SiMe2Ph 287 

SiBu t Ph 2 

12 R 1 = t-Bu; R 2 = Ph 

+ 

Ph 

BnOCH2CHO, BF3 OEt2 

85% 

O SnCl4, CH2Cl2 OEt 0 

96% 

O 

289 

oC, 10 min 

BnO 

H 

O 

H 

O 

EtO 

288 

Ph 

SiMe2Ph 

O 

290 

CO 2Me 

SiBu t Ph 2 

4-(tert-Butyldiphenylsilyl)-2-(ethoxycarbonyl)-2-phenyltetrahydrofuran (290): [304,308] 

To a soln of ethyl ester 289 (40.6 mg, 0.23 mmol) and allyl(tert-butyl)diphenylsilane (12, 

R 1 = t-Bu; R 2 = Ph; 127.8 mg, 0.46 mmol) in CH 2Cl 2 (1.0 mL) was added SnCl 4 (26.0 ìL, 

0.22 mmol) at 08C. After stirring at this temperature for 10 min, the mixture was 

quenched byaddition of Et 3N (0.1 mL) followed byH 2O (5 mL). The aqueous layer was extracted 

with EtOAc and the combined organic layers were washed with brine, dried 

(Na 2SO 4), and concentrated. Purification of the crude mixture bypreparative TLC (silica 

gel, hexane/EtOAc 12:1) afforded tetrahydrofuran 290; yield: 100.1 mg (96%). 

4.4.40.71 Method 71: 

á-Methylenecyclopentanones from Silicon-Directed Nazarov Cyclization 

Allylsilanes, for example, 291, available bythe method of synthesis described in Section 

4.4.40.51, are useful in silicon-directed Nazarov reactions giving á-methylenecyclopentanones, 

for example, 292 (Scheme 116). [309] Of note is the presence of the á-methylenecyclopentanone 

moietyin biologicallyactive natural products. 

Scheme 116 Synthesis of á-Methylenecyclopentanones [309] 

O 

291 

SiMe3 



FeCl3, CH2Cl2 

−10 o C, 1.5 h 

91% 


O 

292



b4,4-Dimethyl-2-methylenecyclopentanone (292); Typical Procedure: [309,310] 

A mixture of anhyd FeCl 3 (390 mg, 2.40 mmol) and dryCH 2Cl 2 (60 mL) under argon was 

cooled to ±108C. Divinyl ketone 291 (243 mg, 1.24 mmol) in CH 2Cl 2 (5 mL) was added dropwise 

to the suspension. The mixture was stirred for 1.5 h and then quenched bythe addition 

of brine (60 mL). The aqueous layer was separated and extracted with CH 2Cl 2 (30 mL). 

The combined extracts were washed with H 2O (30 mL), dried (Na 2SO 4), and concentrated. 

The residue was chromatographed (silica gel, pentane) to give cyclopentanone 292; yield: 

140 mg (91%). 



References 



[1] Sarkar, T. K., Synthesis, (1990), 969. 

[2] Sarkar, T. K., Synthesis, (1990), 1101. 

[3] Dow Corning Corp., USA, US 5756796, (1998); Chem. Abstr., (1998) 129, 28070d. 

[4] Dow Corning Corp., USA, US 5629439, (1997); Chem. Abstr., (1997) 126, 343682s. 

[5] Dow Corning Corp., USA, US 5616760, (1997); Chem. Abstr., (1997) 126, 264198k. 

[6] Dow Corning Corp., USA, US 5596120, (1997); Chem. Abstr., (1997) 126, 131635d. 

[7] Dow Corning Corp., USA, US 5567837, (1996); Chem. Abstr., (1996) 125, 301236y. 

[8] Dow Corning Corp., USA, US 5567834, (1996); Chem. Abstr., (1996) 125, 301234w. 

[9] Colvin, E. W., Silicon in Organic Synthesis, Butterworths: London, (1981). 

[10] Weber, W. P., Silicon Reagents for Organic Synthesis, Springer: New York, (1983). 

[11] Sakurai, H., Ed., In Organosilicon and Bioorganosilicon Chemistry, Structure, Bonding, Reactivity and 

Synthetic Applications, Horwood: Chichester, UK, (1985). 

[12] Colvin, E. W., Silicon Reagents in Organic Synthesis, Academic: London, (1988). 

[13] Patai, S.; Rappoport, Z., Eds., The Chemistry of Organic Silicon Compounds, Parts 1 and 2, Wiley: 

Chichester, UK, (1989). 

[14] Chan, T. H.; Fleming, I., Synthesis, (1979), 761. 

[15] Sakurai, H., Pure Appl. Chem., (1982) 54,1. 

[16] Magnus, P. D.; Sarkar, T.; Djuric, S., In Comprehensive Organometallic Chemistry, Wilkinson, G.; 

Stone, F. G. A.; Abel, E. W., Eds.; Pergamon: New York, (1982); Vol. 7, p 515. 

[17] Sakurai, H., Pure Appl. Chem., (1985) 57, 1759. 

[18] Schinzer, D., Synthesis, (1988), 263. 

[19] Hosomi, A., Acc. Chem. Res., (1988) 21, 200. 

[20] Majetich, G., In Organic Synthesis, Theory & Applications, Hudlicky, T., Ed.; JAI Press: Greenwich, 

CT, (1989), p 173. 

[21] Fleming, I.; Dunogu›s, J.; Smithers, R., Org. React., (1989) 37, 57. 

[22] Sakurai, H., Synlett, (1989), 1. 

[23] Fleming, I., In Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I.; Heathcock, C. H., Eds.; 

Pergamon: Oxford, UK, (1991); Vol. 2, p 563. 

[24] Chan, T. H.; Wang, D., Chem. Rev., (1992) 92, 995. 

[25] Yamamoto, Y.; Asao, N., Chem. Rev., (1993) 93, 2207. 

[26] Chan, T. H.; Wang, D., Chem. Rev., (1995) 95, 1279. 

[27] Masse, C. E.; Panek, J. S., Chem. Rev., (1995) 95, 1293. 

[28] Langkopf, E.; Schinzer, D., Chem. Rev., (1995) 95, 1375. 

[29] Fleming, I.; Barbero, A.; Walter, D., Chem. Rev., (1997) 97, 2063. 

[30] Luh, T.-Y.; Liu, S.-T., The Chemistry of Organic Silicon Compounds, Rappoport, Z.; Apeloig, Y., Eds.; 

Wiley: Chichester, UK, (1998); p 1793. 

[31] Calas, R.; Dunogu›s, J.; Deleris, G.; Piscioti, J., J. Organomet. Chem., (1974) 69, C15. 

[32] Deleris, G.; Dunogu›s, J.; Calas, R., J. Organomet. Chem., (1975) 93, 43. 

[33] Fleming, I.; Pearce, A.; Snowden, R. L., J. Chem. Soc., Chem. Commun., (1976), 182. 

[34] Hosomi, A.; Sakurai, H., Tetrahedron Lett., (1976), 1295. 

[35] Hosomi, A.; Sakurai, H., J. Am. Chem. Soc., (1977) 99, 1673. 

[36] Hayashi, T.; Kabeta, K.; Hamachi, I.; Kumada, M., Tetrahedron Lett., (1983) 24, 2865. 

[37] Hathaway, S. J.; Paquette, L. A., J. Org. Chem., (1983) 48, 3351. 

[38] Chan, T. H.; Wang, D., Tetrahedron Lett., (1989) 30, 3041. 

[39] Komatsu, N.; Uda, M.; Suzuki, H.; Takahashi, T.; Domae, T.; Wada, M., Tetrahedron Lett., (1997) 38, 

7215. 

[40] Aggarwal, V. K.; Vennall, G. P., Synthesis, (1988), 1822. 

[41] Chatgilialoglu, C.; Ferreri, C.; Ballestri, M.; Curran, D. P., Tetrahedron Lett., (1996) 37, 6387. 

[42] Zhang, L.-C.; Sakurai, H.; Kira, M., Chem. Lett., (1997), 129. 

[43] Matsumoto, K.; Oshima, K.; Utimoto, K., J. Org. Chem., (1994) 59, 7152. 

[44] Knölker, H.-J., J. Prakt. Chem., (1997) 339, 304. 

[45] Knölker, H.-J.; Jones, P. G.; Wanzl, G., Synlett, (1998), 613. 

[46] Tietze, L. F.; Schimpf, R., Chem. Ber., (1994) 127, 2235. 

[47] Clive, D. L. J.; Paul, C. C.; Wang, Z., J. Org. Chem., (1997) 62, 7028. 

[48] Brey, W. S., Silicon-29 Nuclear Magnetic Resonance, In Silicon Compounds, Register and Review, 

4th ed., Larson, G. L., Ed.; Petrarch Systems: Bristol, PA, (1987); p 60. 



References 921 

b[49] Sommer, L. H.; Tyler, L. J.; Whitmore, F. C., J. Am. Chem. Soc., (1948) 70, 2872. 

[50] Mironov, V. F.; Nepomnina, V. V., Izv. Akad. Nauk SSSR, Ser. Khim., (1960), 1419; Chem. Abstr., 

(1961) 55, 358. 

[51] Topchiev, A. V.; Nametkin, N. S.; Chernysheva, T. I.; Durgar yan, S. G., Dokl. Akad. Nauk SSSR, 

(1956) 110, 97; Chem. Abstr., (1957) 51, 4979g; Dokl. Chem. (Engl. Trans.), (1956), 545. 

[52] Pillot, J.-P.; Dunogu›s, J.; Calas, R., Tetrahedron Lett., (1976), 1871. 

[53] Slutsky, J.; Kwart, H., J. Am. Chem. Soc., (1973) 95, 8678. 

[54] Yanagisawa, A.; Habaue, S.; Yamamoto, H., J. Am. Chem. Soc., (1991) 113, 5893. 

[55] Knölker, H.-J.; Foitzik, N.; Goesmann, H.; Graf, R.; Jones, P. G.; Wanzl, G., Chem. Eur. J., (1997) 3, 

538. 

[56] Reuter, J. M.; Sinha, A.; Salomon, R. G., J. Org. Chem., (1978) 43, 2438. 

[57] Shimizu, N.; Imazu, S.; Shibata, F.; Tsuno, Y., Bull. Chem. Soc. Jpn., (1991) 64, 1122. 

[58] Hayashi, T.; Kabeta, K.; Kumada, M., Tetrahedron Lett., (1984) 25, 1499. 

[59] Sanji, T.; Iwata, M.; Watanabe, M.; Hoshi, T.; Sakurai, H., Organometallics, (1998) 17, 5068. 

[60] Shono, T.; Matsumura, Y.; Katoh, S.; Kise, N., Chem. Lett., (1985), 463. 

[61] Yoshida, J.-i.; Muraki, K.; Funahashi, H.; Kawabata, N., J. Org. Chem., (1986) 51, 3996. 

[62] Rajaonah, M.; Rock, M. H.; BØguØ, J.-P.; Bonnet-Delpon, D.; Condon, S.; NØdØlec, J.-Y., Tetrahedron 

Lett., (1998) 39, 3137. 

[63] Torii, S.; Tanaka, H.; Katoh, T.; Morisaki, K., Tetrahedron Lett., (1984) 25, 3207. 

[64] Wilson, S. R.; Phillips, L. R.; Natalie, K. J., Jr., J. Am. Chem. Soc., (1979) 101, 3340. 

[65] Andrianome, M.; Delmond, B., Tetrahedron Lett., (1985) 26, 6341. 

[66] Sarkar, T. K.; Andersen, N. H., Tetrahedron Lett., (1978), 3513. 

[67] Andersen, N. H.; McCrae, D. A.; Grotjahn, D. B.; Gabhe, S. Y.; Theodore, L. J.; Ippolito, R. M.; 

Sarkar, T. K., Tetrahedron, (1981) 37, 4069. 

[68] Trost, B. M.; Chan, D. M. T., J. Am. Chem. Soc., (1983) 105, 2315. 

[69] Trost, B. M.; Chan, D. M. T.; Nanninga, T. N., Org. Synth., (1984) 62, 58. 

[70] Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H., Chem. Pharm. Bull., (1983) 31, 86. 

[71] Schlosser, M.; Dahan, R.; Cottens, S., Helv. Chim. Acta, (1984) 67, 284. 

[72] Desponds, O.; Franzini, L.; Schlosser, M., Synthesis, (1997), 150. 

[73] Danheiser, R. L.; Takahashi, T.; Bertók, B.; Dixon, B. R., Tetrahedron Lett., (1993) 34, 3845. 

[74] Schlosser, M.; Desponds, O.; Lehmann, R.; Moret, E.; Rauchschwalbe, G., Tetrahedron, (1993) 49, 

10175. 

[75] Moret, E., Ph.D. Thesis, Universityof Lausanne, (1980). 

[76] Moret, E.; Franzini, L.; Schlosser, M., Chem. Ber., (1997) 130, 335. 

[77] Franciotti, M.; Mordini, A.; Taddei, M., Synlett, (1992), 137. 

[78] Degl Innocenti, A.; Mordini, A.; Pagliai, L.; Ricci, A., Synlett, (1991), 155. 

[79] Hosomi, A.; Ando, M.; Sakurai, H., Chem. Lett., (1984), 1385. 

[80] Negishi, E.-i.; Luo, F.-T.; Rand, C. L., Tetrahedron Lett., (1982) 23, 27. 

[81] Organ, M. G.; Winkle, D. D., J. Org. Chem., (1997) 62, 1881. 

[82] Itoh, K.; Yogo, T.; Ishii, Y., Chem. Lett., (1977), 103. 

[83] Hayashi, T.; Konishi, M.; Okamoto, Y.; Kabeta, K.; Kumada, M., J. Org. Chem., (1986) 51, 3772. 

[84] Organ, M. G.; Murray, A. P., J. Org. Chem., (1997) 62, 1523. 

[85] Sugihara, Y.; Ogasawara, K., Synlett, (1994), 665. 

[86] Hayashi, T.; Fujiwa, T.; Okamoto, Y.; Katsuro, Y.; Kumada, M., Synthesis, (1981), 1001. 

[87] Armstrong, R. J.; Weiler, L., Can. J. Chem., (1983) 61, 214. 

[88] Polla, M.; Frejd, T., Tetrahedron, (1993) 49, 2701. 

[89] Saulnier, M. G.; Kadow, J. F.; Tun, M. M.; Langley, D. R.; Vyas, D. M., J. Am. Chem. Soc., (1989) 111, 

8320. 

[90] Loreto, M. A.; Pompei, F.; Tardella, P. A.; Tofani, D., Tetrahedron, (1997) 53, 15853. 

[91] Hayashi, T.; Katsuro, Y.; Kumada, M., Tetrahedron Lett., (1980) 21, 3915. 

[92] Gais, H.-J.; Bülow, G., Tetrahedron Lett., (1992) 33, 461. 

[93] Hevesi, L.; Hermans, B.; Allard, C., Tetrahedron Lett., (1994) 35, 6729. 

[94] Bhushan, V.; Lohray, B. B.; Enders, D., Tetrahedron Lett., (1993) 34, 5067. 

[95] Enders, D.; Lohray, B. B., Angew. Chem., (1987) 99, 359; Angew. Chem. Int. Ed. Engl., (1987) 26, 351. 

[96] Seyferth, D.; Wursthorn, K. R.; Mammarella, R. E., J. Org. Chem., (1977) 42, 3104. 

[97] Seyferth, D.; Wursthorn, K. R.; Lim, T. F. O.; Sepelak, D. J., J. Organomet. Chem., (1979) 181, 293. 

[98] Fleming, I.; Paterson, I., Synthesis, (1979), 446. 

[99] Iio, H.; Ishii, M.; Tsukamoto, M. T.; Tokoroyama, T., Tetrahedron Lett., (1988) 29, 5965. 




b[100] Zhao, C. X.; Romo, D., Tetrahedron Lett., (1997) 38, 6537. 

[101] Henning, R.; Hoffmann, H. M. R., Tetrahedron Lett., (1982) 23, 2305. 

[102] Hoffmann, H. M. R.; Henning, R., Helv. Chim. Acta, (1983) 66, 828. 

[103] Kuroda, C.; Nogami, H.; Ohnishi, Y.; Kimura, Y.; Satoh, J. Y., Tetrahedron, (1997) 53, 839. 

[104] Hoffmann, H. M. R.; Rabe, J., J. Org. Chem., (1985) 50, 3849. 

[105] Giguere, R. J.; Duncan, S. M.; Bean, J. M.; Purvis, L., Tetrahedron Lett., (1988) 29, 6071. 

[106] Giguere, R. J.; Tassely, S. M.; Rose, M. I., Tetrahedron Lett., (1990) 31, 4577. 

[107] Takeda, T.; Watanabe, M.; Rahim, M. A.; Fujiwara, T., Tetrahedron Lett., (1998) 39, 3753. 

[108] Horikawa, Y.; Watanabe, M.; Fujiwara, T.; Takeda, T., J. Am. Chem. Soc., (1997) 119, 1127. 

[109] Hsiao, C.-N.; Shechter, H., Tetrahedron Lett., (1982) 23, 1963. 

[110] Hsiao, C. -N.; Shechter, H., J. Org. Chem., (1988) 53, 2688. 

[111] Hart, D. J.; Wu, W.-L., Tetrahedron Lett., (1996) 37, 5283. 

[112] Ranasinghe, M. G.; Fuchs, P. L., J. Am. Chem. Soc., (1989) 111, 779. 

[113] Fuchs, P. L., personal communication. 

[114] Tsuji, J.; Hara, M.; Ohno, K., Tetrahedron, (1974) 30, 2143. 

[115] Ojima, I., The Chemistry of Organic Silicon Compounds, Part 2, Patai, S.; Rappoport, Z., Eds.; Wiley: 

New York, (1989); p 1479. 

[116] Kira, M.; Hino, T.; Sakurai, H., Tetrahedron Lett., (1989) 30, 1099. 

[117] Hayashi, T.; Hengrasmee, S.; Matsumoto, Y., Chem. Lett., (1990), 1377. 

[118] Hatanaka, Y.; Goda, K.-i.; Yamashita, F.; Hiyama, T., Tetrahedron Lett., (1994) 35, 7981. 

[119] Hayashi, T.; Matsumoto, Y.; Morikawa, I.; Ito, Y., Tetrahedron: Asymmetry, (1990) 1, 151. 

[120] Kitayama, K.; Tsuji, H.; Uozumi, Y.; Hayashi, T., Tetrahedron Lett., (1996) 37, 4169. 

[121] Hiyama, T., personal communication. 

[122] Hayashi, T., personal communication. 

[123] Obora, Y.; Tsuji, Y.; Kawamura, T., J. Am. Chem. Soc., (1993) 115, 10414. 

[124] Obora, Y.; Tsuji, Y.; Kawamura, T., J. Am. Chem. Soc., (1995) 117, 9814. 

[125] Furuya, N.; Sukawa, T., J. Organomet. Chem., (1975) 96, C1. 

[126] Nishiyama, H.; Yokoyama, H.; Narimatsu, S.; Itoh, K., Tetrahedron Lett., (1982) 23, 1267. 

[127] Nishiyama, H.; Narimatsu, S.; Itoh, K., Tetrahedron Lett., (1981) 22, 5289. 


[129] Trost, B. M.; Coppola, B. P., J. Am. Chem. Soc., (1982) 104, 6879. 

[130] Knochel, P.; Rao, S. A., J. Am. Chem. Soc., (1990) 112, 6146. 

[131] Hollingworth, G. J.; Lee, T. V.; Sweeney, J. B., Tetrahedron Lett., (1992) 33, 5591. 

[132] Kang, K.-T.; Kim, S. S.; Lee, J. C., Tetrahedron Lett., (1991) 32, 4341. 

[133] Carr, S. A.; Weber, W. P., J. Org. Chem., (1985) 50, 2782. 

[134] Wu, M.-Y.; Yang, F.-Y.; Cheng, C.-H., J. Org. Chem., (1999) 64, 2471. 

[135] Hwu, J. R.; Lin, L. C.; Liaw, B. R., J. Am. Chem. Soc., (1988) 110, 7252. 

[136] Tsuji, Y.; Funato, M.; Ozawa, M.; Ogiyama, H.; Kajita, S.; Kawamura, T., J. Org. Chem., (1996) 61, 

5779. 

[137] Hanamoto, T.; Sugino, A.; Kikukawa, T.; Inanaga, J., Bull. Soc. Chim. Fr., (1997) 134, 391. 

[138] Suginome, M.; Matsumoto, A.; Ito, Y., J. Am. Chem. Soc., (1996) 118, 3061. 

[139] Suginome, M.; Iwanami, T.; Matsumoto, A.; Ito, Y., Tetrahedron: Asymmetry, (1997) 8, 859. 

[140] Suginome, M., personal communication. 

[141] Obora, Y.; Tsuji, Y.; Kawamura, T., Organometallics, (1993) 12, 2853. 

[142] Fleming, I.; Thomas, A. P., J. Chem. Soc., Chem. Commun., (1985), 411. 

[143] Fleming, I.; Thomas, A. P., J. Chem. Soc., Chem. Commun., (1986), 1456. 

[144] Fleming, I.; Higgins, D.; Lawrence, N. J.; Thomas, A. P., J. Chem. Soc., Perkin Trans. 1, (1992), 3331. 

[145] Fleming, I.; Newton, T. W., J. Chem. Soc., Perkin Trans. 1, (1984), 1805. 

[146] Fleming, I.; Marchi, D., Jr., Synthesis, (1981), 560. 

[147] Fleming, I.; Terrett, N. K., J. Organomet. Chem., (1984) 264, 99. 

[148] Fleming, I.; Terrett, N. K., Tetrahedron Lett., (1983) 24, 4151. 

[149] Laycock, B.; Kitching, W.; Wickham, G., Tetrahedron Lett., (1983) 24, 5785. 

[150] Azzari, E.; Faggi, C.; Gelsomini, N.; Taddei, M., Tetrahedron Lett., (1989) 30, 6067. 

[151] Sisko, J.; Henry, J. R.; Weinreb, S. M., J. Org. Chem., (1993) 58, 4945. 

[152] Goering, H. L.; Kantner, S. S.; Tseng, C. C., J. Org. Chem., (1983) 48, 715. 

[153] Smith, J. G.; Quinn, N. R.; Viswanathan, M., Synth. Commun., (1983) 13, 1. 

[154] Smith, J. G.; Quinn, N. R.; Viswanathan, M., Synth. Commun., (1983) 13, 773. 




b[155] Smith, J. G.; Drozda, S. E.; Petraglia, S. P.; Quinn, N. R.; Rice, E. M.; Taylor, B. S.; Viswanathan, M., 

J. Org. Chem., (1984) 49, 4112. 

[156] Smith, J. G.; Henke, S. L.; Mohler, E. M.; Morgan, L.; Rajan, N. I.; Synth. Commun., (1991) 21, 1999. 

[157] Barbero, A.; García, C.; Pulido, F. J., Tetrahedron Lett., (1999) 40, 6649. 

[158] Blanco, F. J.; Cuadrado, P.; Gonzµlez, A. M.; Pulido, F. J.; Fleming, I., Tetrahedron Lett., (1994) 35, 

8881. 

[159] Fleming, I.; Rowley, M.; Cuadrado, P.; Gonzµlez-Nogel, A. M.; Pulido, F. J., Tetrahedron, (1989) 45, 

413. 

[160] Fleming, I.; Pulido, F. J., J. Chem. Soc., Chem. Commun., (1986), 1010. 

[161] Pulido, F. J., personal communication. 

[162] Fleming, I., In Organocopper Reagents, Taylor, R. J. K., Ed.; Oxford University Press: New York, 

(1994); p 257. 

[163] Asao, K.; Iio, H.; Tokoroyama, T., Synthesis, (1990), 382. 

[164] Araki, S.; Butsugan, Y., J. Chem. Soc., Perkin Trans. 1, (1984), 969. 

[165] Fleming, I.; Sarkar, A. K., J. Chem. Soc., Chem. Commun., (1986), 1199. 

[166] Fleming, I.; Gil, S.; Sarkar, A. K.; Schmidlin, T., J. Chem. Soc., Perkin Trans. 1, (1992), 3351. 

[167] Fleming, I., J. Chem. Soc., Perkin Trans. 1, (1992), 3363. 

[168] Fleming, I.; Kindon, N. D., J. Chem. Soc., Perkin Trans. 1, (1995), 303. 

[169] Palomo, C.; Aizpurua, J. M.; Iturburu, M.; Urchegui, R., J. Org. Chem., (1994) 59, 240. 

[170] Buckle, M. J. C.; Fleming, I.; Gil, S., Tetrahedron Lett., (1992) 33, 4479. 

[171] Fleming, I.; Waterson, D., J. Chem. Soc., Perkin Trans. 1, (1984), 1809. 

[172] Kleijn, H.; Vermeer, P., J. Org. Chem., (1985) 50, 5143. 

[173] Foulon, J. P.; Bourgain-Commerçon, M.; Normant, J. F., Tetrahedron, (1986) 42, 1389. 

[174] Normant, J. F.; Alexakis, A., Synthesis, (1981), 846. 

[175] Trost, B. M.; Matelich, M. C., J. Am. Chem. Soc., (1991) 113, 9007. 

[176] Trost, B. M.; Matelich, M. C., Synthesis, (1992), 151. 

[177] Harmata, M.; Herron, B. F., Synthesis, (1993), 202. 

[178] Foulon, J. P.; Bourgain-Commerçon, M.; Normant, J. F., Tetrahedron, (1986) 42, 1399. 

[179] Majetich, G.; Leigh, A. J., Tetrahedron Lett., (1991) 32, 609. 

[180] Bond, F. T.; Dipietro, R. A., J. Org. Chem., (1981) 46, 1315. 

[181] Narayanan, B. A.; Bunnelle, W. H., Tetrahedron Lett., (1987) 28, 6261. 

[182] Bardot, V.; Gelas-Mialhe, Y.; Gramain, J. -C.; Remuson, R., Tetrahedron: Asymmetry, (1997) 8, 1111. 

[183] Lee, T. V.; Porter, J. R.; Roden, F. S., Tetrahedron Lett., (1988) 29, 5009. 

[184] Harmata, M.; Jones, D. E., J. Org. Chem., (1997) 62, 1578. 

[185] Lee, T. V.; Channon, J. A.; Cregg, C.; Porter, J. R.; Roden, F. S.; Yeoh, H. T.-L., Tetrahedron, (1989) 45, 

5877. 

[186] Anderson, M. B.; Fuchs, P. L., Synth. Commun., (1987) 17, 621. 

[187] Petrov, A. D.; Ponomarenko, V. A.; Snegova, A. D., Dokl. Akad. Nauk SSSR, (1957) 112, 79; Dokl. 

Chem. (Engl. Transl.), (1957), 17. 

[188] Fleming, I.; Pearce, A., J. Chem. Soc., Perkin Trans. 1, (1981), 251. 

[189] Yamazaki, T.; Ishikawa, N., Chem. Lett., (1984), 521. 

[190] Haider, A., Synthesis, (1985), 271. 

[191] Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H., J. Chem. Soc., Chem. Commun., (1982), 1108. 

[192] de Raadt, A.; Stutz, A. E., Carbohydr. Res., (1991) 220, 101. 

[193] Ishihara, T.; Miwatashi, S.; Kuroboshi, M.; Utimoto, K., Tetrahedron Lett., (1991) 32, 1069. 

[194] Liu, H.-J.; Shia, K.-S.; Shang, X.; Zhu, B.-Y., Tetrahedron, (1999) 55, 3803. 

[195] Mikami, K.; Maeda, T.; Kishi, N.; Nakai, T., Tetrahedron Lett., (1984) 25, 5151. 

[196] Wada, M.; Shigehira, T.; Akiba, K.-Y., Tetrahedron Lett., (1985) 26, 5191. 

[197] Russell, A. T.; Procter, G., Tetrahedron Lett., (1987) 28, 2045. 

[198] Ward, R. A.; Procter, G., Tetrahedron, (1995) 51, 12821. 

[199] Jain, N. F.; Cirillo, P. F.; Schaus, J. V.; Panek, J. S., Tetrahedron Lett., (1995) 36, 8723. 

[200] Sparks, M. A.; Panek, J. S., J. Org. Chem., (1991) 56, 3431. 

[201] Panek, J. S.; Clark, T. D., J. Org. Chem., (1992) 57, 4323. 

[202] Panek, J. S.; Yang, M., J. Am. Chem. Soc., (1991) 113, 9868. 

[203] Matassa, V. G.; Jenkins, P. R.; Kümin, A.; Damm, L.; Schreiber, J.; Felix, D.; Zass, E.; 

Eschenmoser, A., Isr. J. Chem., (1989) 29, 321. 

[204] Russell, A. T.; Procter, G., Tetrahedron Lett., (1987) 28, 2041. 

[205] Jenkins, P. R.; Gut, R.; Wetter, H.; Eschenmoser, A., Helv. Chim. Acta, (1979) 62, 1922. 




b[206] Fleming, I.; Percival, A., J. Chem. Soc., Chem. Commun., (1976), 681. 

[207] Fleming, I.; Percival, A., J. Chem. Soc., Chem. Commun., (1978), 178. 

[208] Carter, M. J.; Fleming, I.; Percival, A., J. Chem. Soc., Perkin Trans. 1, (1981), 2415. 

[209] Koreeda, M.; Ciufolini, M. A., J. Am. Chem. Soc., (1982) 104, 2308. 

[210] Oppolzer, W.; Burford, S.; Marazza, F., Helv. Chim. Acta, (1980) 63, 555. 

[211] Burke, S. D.; Strickland, S. M. S.; Powner, T. H., J. Org. Chem., (1983) 48, 454. 

[212] Sarkar, T. K.; Ghosh, S. K.; Subba Rao, P. S. V.; Satapathi, T. K., Tetrahedron Lett., (1990) 31, 3461. 

[213] Sarkar, T. K.; Ghosh, S. K.; Subba Rao, P. S. V.; Satapathi, T. K.; Mamdapur, V. R., Tetrahedron, 

(1992) 48, 6897. 

[214] Sarkar, T. K.; Ghorai, B. K.; Nandy, S. K.; Mukherjee, B.; Banerji, A., J. Org. Chem., (1997) 62, 6006. 

[215] Mak, C. C.; Chan, K. S., J. Chem. Soc., Perkin Trans. 1, (1993), 2143. 

[216] Mak, C. C.; Tse, M. K.; Chan, K. S., J. Org. Chem., (1994) 59, 3585. 

[217] Landais, Y.; Planchenault, D.; Weber, V., Tetrahedron Lett., (1994) 35, 9549. 

[218] Bulugahapitiya, P.; Landais, Y.; Parra-Rapado, L.; Planchenault, D.; Weber, V., J. Org. Chem., (1997) 

62, 1630. 

[219] Davies, H. M. L.; Hansen, T.; Rutberg, J.; Bruzinski, P. R., Tetrahedron Lett., (1997) 38, 1741. 

[220] Hwu, J. R.; Gilbert, B. A.; Lin, L. C.; Liaw, B. R., J. Chem. Soc., Chem. Commun., (1990), 161. 

[221] Tietze, L. F.; Wünsch, J. R., Synthesis, (1990), 985. 

[222] Marumoto, S.; Kuwajima, I., J. Am. Chem. Soc., (1993) 115, 9021. 

[223] Gibson, C.; Buck, T.; Noltemeyer, M.; Brückner, R., Tetrahedron Lett., (1997) 38, 2933. 

[224] Chatgilialoglu, C.; Ballestri, M.; Vecchi, D.; Curran, D. P., Tetrahedron Lett., (1996) 37, 6383. 

[225] Chan, T. H.; Labrecque, D., Tetrahedron Lett., (1991) 32, 1149. 

[226] Soderquist, J.A.; Santiago, B., Tetrahedron Lett., (1989) 30, 5693. 

[227] Sarkar, T. K.; Ghorai, B. K., J. Chem. Soc., Chem. Commun., (1992), 1184. 

[228] Sarkar, T. K.; Ghorai, B. K., unpublished results. 

[229] Ollivier, J.; Salaün, J., Synlett, (1994), 949. 

[230] Hayashi, T.; Iwamura, H.; Uozumi, Y., Tetrahedron Lett., (1994) 35, 4813. 

[231] Rajagopalan, S.; Zweifel, G., Synthesis, (1984), 113. 

[232] Mohr, P., Tetrahedron Lett., (1995) 36, 2453. 

[233] Tietze, L. F.; Neumann, T.; Kajino, M.; Pretor, M., Synthesis, (1995), 1003. 

[234] Crowe, W. E.; Goldberg, D. R.; Zhang, Z. J., Tetrahedron Lett., (1996) 37, 2117. 

[235] Brümmer, O.; Rückert, A.; Blechert, S., Chem. Eur. J., (1997) 3, 441. 

[236] Schneider, M. F.; Lucas, N.; Velder, J.; Blechert, S., Angew. Chem., (1997) 109, 257; Angew. Chem. 

Int. Ed. Engl., (1997) 36, 257. 

[237] Schuster, M.; Lucas, N.; Blechert, S., Chem. Commun. (Cambridge), (1997), 823. 

[238] Fujiwara, T.; Takamori, M.; Takeda, T., Chem. Commun. (Cambridge), (1998), 51. 

[239] Olofsson, K.; Larhed, M.; Hallberg, A., J. Org. Chem., (1998) 63, 5076. 

[240] Bardot, V.; Remuson, R.; Gelas-Mialhe, Y.; Gramain, J.-C., Synlett, (1996), 37. 

[241] Araki, S.; Ito, H.; Butsugan, Y., J. Org. Chem., (1988) 53, 1831. 

[242] Krief, A.; Dumont, W.; Markó, I. E.; Murphy, F.; Vanherck, J.-C.; Duval, R.; Ollevier, T.; Abel, U., 

Synlett, (1998), 1219. 

[243] Ryter, K.; Livinghouse, T., J. Org. Chem., (1997) 62, 4842. 

[244] Ramon, D. J.; Yus, M., Tetrahedron, (1993) 49, 10103. 

[245] Minato, A.; Suzuki, K.; Tamao, K.; Kumada, M., Tetrahedron Lett., (1984) 25, 83. 

[246] Hosomi, A.; Sakata, Y.; Sakurai, H., Tetrahedron Lett., (1985) 26, 5175. 

[247] Hosomi, A.; Otaka, K.; Sakurai, H., Tetrahedron Lett., (1986) 27, 2881. 

[248] Kang, K.-T.; U, J. S.; Park, D. K.; Kim, J. K.; Kim, W. J., Bull. Korean Chem. Soc., (1995) 16, 464. 

[249] Majetich, G.; Nishidie, H.; Zhang, Y., J. Chem. Soc., Perkin Trans. 1, (1995), 453. 

[250] Kang, K.-T.; Sung, T. M.; Kim, J. K.; Kwon, Y. M., Synth. Commun., (1997) 27, 1173. 

[251] Mordini, A.; Palio, G.; Ricci, A.; Taddei, M., Tetrahedron Lett., (1988) 29, 4991. 

[252] Soderquist, J. A.; Santiago, B.; Rivera, I., Tetrahedron Lett., (1990) 31, 4981. 

[253] Ni, Z.-J.; Luh, T.-Y., J. Chem. Soc., Chem. Commun., (1988), 1011. 

[254] Fugami, K.; Oshima, K.; Utimoto, K.; Nozaki, H., Tetrahedron Lett., (1986) 27, 2161. 

[255] Fugami, K.; Hibino, J. -I.; Nakatsukasa, S.; Matsubara, S.; Oshima, K.; Utimoto, K.; Nozaki, H., 

Tetrahedron, (1988) 44, 4277. 

[256] Pornet, J.; Khouz, B.; Miginiac, L., Tetrahedron Lett., (1985) 26, 1861. 

[257] Pornet, J.; Rayadh, A.; Miginiac, L., Tetrahedron Lett., (1986) 27, 5479. 

[258] Sarkar, T. K.; Ghosh, S. K., Tetrahedron Lett., (1987) 28, 2061. 




b[259] Sarkar, T. K.; Ghosh, S. K.; Satapathi, T. K., Tetrahedron, (1990) 46, 1885. 

[260] Barluenga, J.; Fernµndez-Simón, J. L.; Concellón, J. M.; Yus, M., Tetrahedron Lett., (1989) 30, 5927. 

[261] Ochiai, M.; Sumi, K.; Fujita, E.; Tada, S.-i., Chem. Pharm. Bull., (1983) 31, 3346. 

[262] Hori, Y.; Mitsudo, T.-a.; Watanabe, Y., Bull. Chem. Soc. Jpn., (1988) 61, 3011. 

[263] Terao, J.; Torii, K.; Saito, K.; Kambe, N.; Baba, A.; Sonoda, N., Angew. Chem., (1998) 110, 2798; 

Angew. Chem. Int. Ed., (1998) 37, 2653. 

[264] Pillot, J.-P.; DØlØris, G.; Dunogu›s, J.; Calas, R., J. Org. Chem., (1979) 44, 3397. 

[265] Saito, S.; Shimada, K.; Yamamoto, H.; Martinez de Marigorta, E.; Fleming, I., Chem. Commun. 

(Cambridge), (1997), 1299. 

[266] Tanigawa, Y.; Fuse, Y.; Murahashi, S.-I., Tetrahedron Lett., (1982) 23, 557. 

[267] Shiragami, H.; Kawamoto, T.; Utimoto, K.; Nozaki, H., Tetrahedron Lett., (1986) 27, 589. 

[268] Shiragami, H.; Kawamoto, T.; Imi, K.; Matsubara, S.; Utimoto, K.; Nozaki, H., Tetrahedron, (1988) 

44, 4009. 

[269] Wang, K. K.; Yang, K. E., Tetrahedron Lett., (1987) 28, 1003. 

[270] Wang, K. K.; Dhumrongvaraporn, S., Tetrahedron Lett., (1987) 28, 1007. 

[271] Fleming, I.; Au-Yeung, B.-W., Tetrahedron, (1981) 37 (Suppl. 9), 13. 

[272] Fujii, K.; Hara, O.; Sakagami, Y., Biosci. Biotech. Biochem., (1997) 61, 1394. 

[273] Matsuda, I.; Kato, T.; Sato, S.; Izumi, Y., Tetrahedron Lett., (1986) 27, 5747. 

[274] Tzeng, D.; Weber, W. P., J. Org. Chem., (1981) 46, 693. 

[275] Wang, D.; Chan, T.-H., J. Chem. Soc., Chem. Commun., (1984), 1273. 

[276] Trost, B. M.; Yoshida, J.-i.; Lautens, M., J. Am. Chem. Soc., (1983) 105, 4494. 

[277] Molander, G. A.; Shubert, D. C., Tetrahedron Lett., (1986) 27, 787. 

[278] Wilson, S. R.; Zucker, P. A., J. Org. Chem., (1988) 53, 4682. 

[279] Salomon, R. G.; Coughlin, D. J., J. Org. Chem., (1979) 44, 3784. 

[280] Cozzi, P. G.; Tagliavini, E.; Umani-Ronchi, A., Gazz. Chim. Ital., (1997) 127, 247. 

[281] Denmark, S. E.; Coe, D. M.; Pratt, N. E.; Griedel, B. D., J. Org. Chem., (1994) 59, 6161. 

[282] Nakajima, M.; Saito, M.; Shiro, M.; Hashimoto, S.-i., J. Am. Chem. Soc., (1998) 120, 6419. 

[283] Pellissier, H.; Toupet, L.; Santelli, M., J. Org. Chem., (1994) 59, 1709. 

[284] Brain, C. T.; Thomas, E. J., Tetrahedron Lett., (1997) 38, 2387. 

[285] Organ, M. G.; Winkle, D. D.; Huffmann, J., J. Org. Chem., (1997) 62, 5254. 

[286] Lee, T. V.; Boucher, R. J.; Rockell, C. J. M., Tetrahedron Lett., (1988) 29, 689. 

[287] Kobayashi, S.; Nishio, K., J. Org. Chem., (1994) 59, 6620. 

[288] Wang, Z.; Kisanga, P.; Verkade, J. G., J. Org. Chem., (1999) 64, 6459. 

[289] Suginome, M.; Iwanami, T.; Ito, Y., J. Org. Chem., (1998) 63, 6096. 

[290] Franciotti, M.; Mann, A.; Mordini, A.; Taddei, M., Tetrahedron Lett., (1993) 34, 1355. 

[291] Hayashi, T.; Okamoto, Y.; Kabeta, K.; Hagihara, T.; Kumada, M., J. Org. Chem., (1984) 49, 4224. 

[292] Sarkar, T. K.; Gangopadhyay, P.; Ghorai, B. K.; Nandy, S. K.; Fang, J.-M., Tetrahedron Lett., (1998) 

39, 8365. 

[293] Soderquist, J. A.; Rane, A. M.; Lopez, C. J., Tetrahedron Lett., (1993) 34, 1893. 

[294] Tokoroyama, T.; Pan, L.-R., Tetrahedron Lett., (1989) 30, 197. 

[295] Corey, E. J.; Burk, R. M., Tetrahedron Lett., (1987) 28, 6413. 

[296] Snider, B. B.; Lu, Q., J. Org. Chem., (1994) 59, 8065. 

[297] Tietze, L. F.; Schünke, C., Angew. Chem., (1995) 107, 1901; Angew. Chem. Int. Ed. Engl., (1995) 34, 

1731. 


[299] Cleary, D. G.; Paquette, L. A., Synth. Commun., (1987) 17, 497. 

[300] Trost, B. M.; Mac Pherson, D. T., J. Am. Chem. Soc., (1987) 109, 3483. 

[301] Molander, G. A.; Shubert, D. C., J. Am. Chem. Soc., (1987) 109, 6877. 

[302] Trost, B. M.; Seoane, P. R., J. Am. Chem. Soc., (1987) 109, 615. 

[303] Hoffmann, H. M. R., personal communication. 

[304] Akiyama, T.; Ishikawa, K.; Ozaki, S., Chem. Lett., (1994), 627. 

[305] Akiyama, T.; Yasusa, T.; Ishikawa, K.; Ozaki, S., Tetrahedron Lett., (1994) 35, 8401. 

[306] Panek, J. S.; Beresis, R., J. Org. Chem., (1993) 58, 809. 

[307] Schinzer, D.; Panke, J. G., J. Org. Chem., (1996) 61, 4496. 

[308] Akiyama, T., personal communication. 

[309] Kang, K.-T.; Kim, S. S.; Lee, J. C.; U, J. S., Tetrahedron Lett., (1992) 33, 3495. 

[310] Kang, K.-T., personal communication. 

[311] Blechert, S., personal communication. 



b

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