ca01 only detailed ToC 1..24

1.1.2 Nickel–Allyl Complexes 45
Scheme 21 Regio- and Stereochemistry of Nickel-Catalyzed Allylations [43,47,48]
( ) 5
35
OTES
or
OTES
Ar 1 MgBr, NiCl2(dppf)
OTES Ar 1
MeO PPh 2
37
PhMgBr, NiCl 2(dppf) Ph
major isomer
MeMgBr, NiCl2(PPh3)2 3
73%
EtMgBr, NiCl2(PPh 3) 2 3
82%
Scheme 22 Asymmetric Alkylation of Allylic Ethers [51]
Ph
OMe
Ph
EtMgBr, Ni(cod) 2 2
(S,S-Chiraphos) Ph
91%
( ) 5
36 major isomer
38 99:1 regioselectivity
( ) 5
99:1 regioselectivity
3-Phenylbut-1-ene (36): [43]
NiCl 2(dppf) (13.7 mg, 0.04 mmol) was added to a 25-mL two-necked flask equipped with a
stirring bar, a septum, and a three-way stopcock. The vessel was then cooled to –788C,
evacuated, and filled with argon. (E)-1-(Triethylsiloxy)but-2-ene (35; 373 mg, 2.0 mmol)
and 1.2 M PhMgBr in Et 2O (3.3 mL, 4.0 mmol) were then added. The resulting mixture
was stirred at rt for 4 h, and hydrolyzed with 10% HCl (5 mL) at 0 8C. An appropriate internal
standard (normally an alkane) was added to the organic layer. GC analysis of the organic
layer indicated the formation of 0.22 mmol (11%) of (E)-1-phenylbut-2-ene,
0.02 mmol (1%) of (Z)-1-phenylbut-2-ene, and 1.76 mmol (88%) of 3-phenylbut-1-ene (36).
The organic layer and Et 2O extracts from the aqueous layer were combined, washed
with sat. NaHCO 3 soln and then H 2O, and dried (Na 2SO 4). After evaporation of the solvent,
bulb-to-bulb distillation (95–110 8C bath temp/20 Torr) of the residue gave 224 mg (85%) of
a mixture of coupling products, which were separated by preparative GC (Silicone DC550
30% on Celite); no isolated yields were reported.
(E)-1-(Diphenylphosphino)-5-methylundec-3-ene (38); Typical Procedure: [47]
In a glovebox, NiCl 2(PPh 3) 2 (3; 8.8 mg, 13 ìmol) was transferred to a 10-mL flame-dried
round-bottomed flask. The flask was then sealed with a rubber septum, removed from
the glovebox, and kept under argon. (E)-1-(Diphenylphosphino)-3-methoxyundec-4-ene
(37; 1.0 g, 0.27 mmol) was dissolved in anhyd THF (1.7 mL), and the resulting soln was
then added by cannula to the original flask containing the catalyst. The soln was cooled
to 08C, MeMgBr (1.0 mL, 1.3 mmol) was added in a dropwise fashion, and the mixture was
stirred at 22 8C for 18h under argon. The mixture was cooled to 08C and quenched by the
addition of H 2O (1.0 mL). After addition of more H 2O (15 mL), the mixture was washed
R
Et
73% ee
Ph
PPh 2
PPh 2
for references see p 79