ca01 only detailed ToC 1..24

48 Science of Synthesis 1.1 Organometallic Complexes of Nickel
Scheme 26 Nickel-Catalyzed Coupling of an Allylic Acetate, an Alkyne, and an Organotin
[58–60]
R 1
Cl
+
R 2
H + R SnBu3 3
Ni(acac) 2 1
DIBAL-H
67−83%
Carbonylative cyclizations have also been developed that likely involve the insertion of
alkynes into nickel–ð-allyl complexes. [61,62] Chiusoli, who was the pioneer in this area,
demonstrated that either cyclic or acyclic products may be isolated depending on the concentration
of methanol (Scheme 27). Allyl halides are the more commonly used allyl complex
precursor, and enals are also utilized; an example of the latter is the formation of 44
and 45. [63]
Scheme 27 Carbonylative Cyclizations of Nickel–ð-Allyl Complexes [61–63]
OC CO
OC Ni
Cl
CO + H H
CO, MeOH
O Ni
Cl
OTMS
Cl
Ni Ni
Cl
TMSO R1 R1 +
R 3
R 2
O
OMe
if high conc. of MeOH
R 3
CO, MeOH
R 2 R 1
O
44
OMe
or
+
R 3
R 3
R 2
43
O
H
R 1
OMe
O
if low conc. of MeOH
R 2 R 1
(Z)-3-Butyl-1-phenylhepta-3,6-dien-1-yne (43,R 1 =H;R 2 = Bu; R 3 = Ph); Typical Procedure: [58]
To a soln of [Ni(acac) 2](1; 26 mg, 0.1 mmol) in THF (5 mL) was added 1.0 M DIBAL-H in toluene
(0.1 mL, 0.1 mmol) at 0 8C under N 2, and the mixture was stirred for 5 min. To this
black soln were then added tributyl(phenylethynyl)stannane (380 mg, 0.97 mmol), hex-1yne
(99 mg, 1.21 mmol), 3-chloroprop-1-ene (73 mg, 0.95 mmol), at 08C, and then the mixture
was stirred at reflux for 1 h. To this soln was added aq NH 4F (30 mL), and stirring was
continued for 30 min to remove the Bu 3SnCl. After filtration through Celite, the aqueous
layer was extracted with Et 2O (40 mL ” 3). The combined organic layers were washed with
brine, dried (MgSO 4) for 30 min, filtered, and concentrated in vacuo [40 8C (bath)/25 Torr].
The residue was purified by column chromatography, R f = 0.64 (silica gel, hexane) to give
43 as a pale yellow oil; yield: 149 mg (70%). An analytical sample of the product was obtained
by bulb-to-bulb distillation [140 8C (oven)/4 Torr). The isomeric purity of the obtained
product was determined by 1 H NMR and GC.
O
45
OMe
OMe