ca01 only detailed ToC 1..24

1.1.2 Nickel–Allyl Complexes 47
Scheme 24 Addition of Grignard Reagents to Allylic Alcohols [52–55]
MeMgBr, NiCl2(PPh3) 2 3
Bu +
50%
OH
t But But 40
41 4:1
42
4-tert-Butyl-1-methyl-1-vinylcyclohexane (41): [52]
A 0.74 M soln of MeMgBr in Et 2O (35 mL) was distilled under N 2 nearly to dryness, and dry
benzene (20 mL), NiCl 2(PPh 3) 2 (3; 417 mg), and a soln of a 5:3 mixture of cis- and trans-isomers
of 40 (1.00 g, 5.5 mmol) in dry benzene (15 mL) were added successively. The mixture
was heated at reflux under N 2 for 24 h, and sat. NH 4Cl soln (25 mL) was added. The
organic layer was washed with H 2O, dried (Na 2SO 4), and evaporated. Distillation of the residue
afforded a 77:20 mixture of 41 and 42; yield: 500 mg (50%); bp 93–988C/16 Torr, accompanied
by a 3% yield of the diastereomer of 41.
1.1.2.8 Method 8:
Additionof Stabilized Nucleophiles to Nickel–Allyl Complexes
The allylic alkylation with weak nucleophiles employing nickel catalysts is generally not
as efficient as the corresponding palladium-catalyzed methods. However, allylic acetates,
allyl phenyl ethers, and allylic carbonates undergo efficient couplings with amines, phenols,
and malonates in the presence of nickel(0) catalysts (Scheme 25). [56,57]
Scheme 25 Addition of Weak Nucleophiles to Allylic
Acetates, Carbonates, and Ethers [56,57]
OR 1
+
NuH
R1 = Ac, Ph, CO2Me Nu = NEt2, OPh, CH(CO2R2 ) 2
Ni(dppe)2 Nu
1.1.2.9 Method 9:
Alkyne Insertions with Nickel–Allyl Complexes
Migratory insertion of an alkyne into a nickel–ð-allyl complex has not been rigorously established.
However, this mechanistic scenario has been postulated in several synthetically
useful processes. Ikeda has demonstrated that treatment of a mixture of allyl chlorides,
terminal alkynes, and alkynyltin reagents with catalytic amounts of nickel(0) without
phosphine leads to the production of conjugated enynes (e.g., 43; Scheme 26). [58–60]
Whereas couplings with allyl chlorides proceed in high yield, the analogous procedure
with allyl acetates and allyl carbonates is less efficient. Interestingly, reactions carried
out in the presence of triphenylphosphine afford the product derived from direct coupling
of the allyl chloride and alkynyltin. [60] Both inter- and intramolecular variants are
quite general.
for references see p 79