Page 758 - Advanced Organic Chemistry Part B - Reactions & Synthesis

734 H
H O
O PdCl (PPh ) N
2
CHAPTER 8 N DIBAL - H 3 2
O
Reactions Involving O O THF/DMF, 70°C O
Transition Metals CO TIPS HO
HO 2 CO 2 TIPS
Br + (Bu) Sn
3
70%
Ref. 202
The Stille coupling reaction is very versatile with respect to the functionality that
can be carried in both the halide and the tin reagent. Groups such as ester, nitrile,
nitro, cyano, and formyl can be present, which permits applications involving “masked
functionality.” For example, when the coupling reaction is applied to 1-alkoxy-2-
butenylstannanes, the double-bond shift leads to a vinyl ether that can be hydrolyzed
to an aldehyde.

CH 3
H
CH 3 Br + (C H ) SnCHCH CHCH 3 Pd(PPh ) CH 3 CHCH CHOC 2 5
3 4
4 9 3
OC H H +
2 5
CH 3
CH 3 CHCH 2 CH O
Ref. 203

Alkenylstannanes react with 1,1-dibromoalkenes to give enynes. 204 These reactions
are thought to involve elimination of the elements of HBr prior to reductive elimination.

2.5% Pd (dba) 3
2
(MeOPh) P
3
PhCH CBr 2 + CH 2 CHSnBu 3 PhC CCH CH 2
i - Pr NEt
2
89%
This reaction has been used in the synthesis of a portion of callipeltoside, a substance
with anticancer activity.
Br
2.5% Pd 2 (dba) 3
+ Bu Sn OH (MeOPh) P OH
H Br 3 3
H i - Pr NEt H
Cl 2 H
Cl
Ref. 205

The most problematic cases for the Stille reaction involve coupling saturated
systems. The tendency for -elimination of alkylpalladium compounds requires special
conditions. Bis-(dialkylamino)cyclohexylphosphines have shown considerable success

202
P. Wipf and P. D. G. Coish, J. Org. Chem., 64, 5053 (1999).
203 A. Duchene and J.-P. Quintard, Synth. Commun., 15, 873 (1987).
204 W. Shen and L. Wang, J. Org. Chem., 64, 8873 (1999).
205
H. F. Olivo, F. Velazquez, and H. C. Trevisan, Org. Lett., 2, 4055 (2000).