Regioselectivity of the Reactions of Heteroatom-Stabilized Allyl ...

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678 Scheme 39 Scheme 40 222 through 2-(trimethylsilyl)-2,5-dihydrothiophene 1,1-dioxide 220 which is obtained by lithiation and reaction with Me3SiCl‚NaI. 135 5. Allyl Dithiocarbamates (CdC−C−S−CSNR2) Pentadienyl dithiocarbamate 223 is alkylated in the R-position (Scheme 39). 136 Product 224 undergoes presumably a double [3,3]-sigmatropic rearrangement to form 226. 137 Treatment of the latter with MeI gives 1-iodo-2,4-(E,E)-dienes 225 (or tetraenes depending on R). 138 Pheromone synthesis has proceeded via these steps. 139,140 R-Products 228 and 229 are usually obtained in the reaction of allyl dithiocarbamate anions from 227 with aldehydes via titanium reagents (Scheme 40). 141 In the absence of Ti(O i Pr)4, both the R- and γ-products are observed. 142-144 6. Allylsulfinamides (CdC−C−SONR2) Prepared from allyl alcohols and 4-(chlorosulfenyl)morpholine in the presence of triethylamine, allylsulfinamides 230 undergo R-alkylation apparently with high regioselectivity to 231 (Scheme 41), 145 although Julia reported a low diastereoselectivity except for R 1 ) p-Me-C6H4, R 2 ) H. 146 No isomerization of the double bond in 231 was detected after the alkylation. Reaction of 230 with aldehydes gives the R-anti-adducts (�-hydroxysulfinamides) 232 which are unstable and can be converted into the corresponding polyene 233 (mainly E product) by heating under reflux in toluene (Scheme 41). 145 The yield of the alkyl sulfide anion is improved by using methyllithium as the metalating agent since butyllithium can lead to side reactions. Scheme 41 7. Allyl Sulfoximines (CdC−C−SONR) The thermal rearrangement of allylic sulfoximines 234 to allylic sulfinamides 236 can occur thermally but only in a few cases. 147a,b However under palladium(0) catalysis this rearrangement is a general and facile process. 147c,d The rearranged products 236 can be converted to N-protected allylic amines by mild base hydrolysis. The alkylation of allylic sulfoximines 234 (R 1 ) Ph, CH2Ph, R 2 ) Tol) gives R-alkylated products 235 as mixtures of diastereoisomers. 148 An optically active allylic sulfoximine gave an R-alkylated product as a single diastereoisomer. 147c Reaction of lithiated 234 (R 1 ) Ph; R 2 ) Tol) with benzaldehyde gave a 5.3:1 mixture of the R-adduct 238 and the γ-product 239, while a similar reaction with pivaldehyde yielded only the R-product 238. 148 In related examples, R-products were exclusively formed from the reaction of lithiated N-tert-butyldiphenylsilyl 149a and N-methyl 149b allylic sulfoximines with aldehydes. Lithiation of racemic N-tosyl allylic sulfoximine 234 (R 1 ) Ts; R 2 ) Ph) followed by quenching with benzaldehyde or isobutyraldehyde gave exclusively the R-product 238 as mixtures of diastereoisomers. 149c The reaction of lithiated sulfoximines 234 with cyclic enones gave mixtures of regio- and diastereoisomers. The regioselectivity is dependent on the nature of the N-substituent. 148,149a,150,151 N-Tosyl derivatives give exclusively R-1,4-products 240, while this orientation of adduct is only slightly favored in the case of the N-phenyl derivatives. N-tert-Butyldiphenylsilyl derivatives, by contrast, favor γ-1,4adducts (241). For acyclic enone cases, the regioselectivity is also influenced by the nature of the R 1 and R 2 on 234 and the reaction conditions, while the diastereoselectivity can be achieved. 149a,150,151a In one case, the addition of acyclic enones to the lithiated N-tosyl-S-allyl-Sphenylsulfoximines in THF at ∼78 °C followed by quenching with acetic acid at same temperature produced exclusively the 1,4-R-adducts 243 with high diastereoselectivity (Scheme 43). 150 Warming a solution of the anionic adducts 242 to room temperature gave the racemic vinylcyclopropanes 244. Diastereomerically pure γ-hydroxyvinyl sulfoximide is obtained with titanium reagents (Scheme 44). 152,153
Scheme 42 Scheme 43 Scheme 44 D. Selenium Allyl phenyl selenides are valuable precursors of allyllithiums and of metalated allyl phenyl selenides. Similar to sulfur-stabilized analogues, anions of allyl selenides undergo reversible 1,3-shifts. Allyl selenoxides also show [2,3]-sigmatropic rearrangements. In general the chemical behavior of these compounds is similar to their sulfur analogues. Thus, allyl phenyl selenide anion 250 reacts with alkyl halides at the R-position to give 251, whereas it is attacked at the γ-terminus by carbonyl com- Scheme 45 679 pounds forming 252. 154 However, a reversed regioselectivity is observed with triethylaluminum “ate” complexes, i.e., R-adducts 253 (predominantly anti) are produced with carbonyl compounds (Scheme 45). 42 Upon transmetalation of 250 with magnesium compounds the regioselectivity is also converted to R. 41 The regioselectivity also depends on the nature of the electrophile. While TMSCl gives predominantly (82:18) R-attack on allyl selenide anions, PhSiMe2Cl forms a mixture of regioisomers R:γ ) 41:59. 155 Increased R-selectivity is achieved with substituents at the γ-position. Similar to allyl sulfides, (phenylseleno)allyllithium 250 undergoes a HMPA mediated conjugate 1,4-Raddition to 2-cyclopentenone. Without HMPA present, R- 254 and γ-1,2-addition 255 are observed together with a little R- 256 and γ-1,4-addition 257 (Scheme 45). 90 As treatment of 247 with n BuLi or methyllithium leads to rapid transmetalation furnishing the allyllithium 248 and alkyl phenyl selenides 249, allyl selenides (cf. 247) are metalated with LDA or lithium 2,2,6,6-tetramethylpiperidide (LTMP) (Scheme 45). 156 E. Nitrogen We discuss here acylic allylamines, their functionalized derivatives (including phosphoramides, Nnitrosoallylamines, nitropropenes, allylimines, allylamides, and ureas) and analogous cyclic amines (e.g., pyrrolidine) together with allyl derivatives of heterocycles (e.g., benzotriazole, carbazole).
Page 1 and 2: Regioselectivity of the Reactions o
Page 3 and 4: Alan Katritzky is Kenan Professor a
Page 5 and 6: Scheme 3 Scheme 4 of γ-attack 11 a
Page 7 and 8: Scheme 10 Scheme 11 predominantly a
Page 9 and 10: Scheme 16 Scheme 17 106) (Scheme 16
Page 11 and 12: Scheme 25 Scheme 26 γ-attack in th
Page 13: Scheme 35 Scheme 36 Treatment of mo
Page 17 and 18: 3. Allylphosphoramides (CdC−C−N
Page 19 and 20: Scheme 58 steric bulk of the carbon
Page 21 and 22: Scheme 65 Scheme 66 lent stereosele
Page 23 and 24: Scheme 72 Scheme 73 te ester can be
Page 25 and 26: Scheme 79 Scheme 80 b. Aminosilyl-S
Page 27 and 28: Protonation with tert-butyl alcohol
Page 29 and 30: Scheme 93 Scheme 94 hydes (Scheme 9
Page 31 and 32: Scheme 100 In reactions of the ally
Page 33 and 34: Scheme 110 Scheme 111 uents in the
Page 35 and 36: The γ-alkyl-substituted allylic an
Page 37 and 38: Scheme 126. Two Different Gem-Heter
Page 39 and 40: Scheme 135 2. γ-Alkoxyallyl Sulfon
Page 41 and 42: Scheme 146 765 762 768 769 (Scheme
Page 43 and 44: VI. Allyl Anions Stabilized by Thre
Page 45 and 46: Scheme 162. Allyl Anions Stabilized
Page 47 and 48: Scheme 169 Scheme 170 enantiomeric
Page 49 and 50: transition structures 876 of the C(
Page 51 and 52: and ketones if the reaction is carr
Page 53 and 54: silane anions 486 is increased with
Page 55 and 56: (67) Hoppe, D.; Lichtenberg, F. Ang
Page 57 and 58: (287) Gil, J. F.; Ramon, D. J.; Yus

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