Page 757 - Advanced Organic Chemistry Part B - Reactions & Synthesis

The Stille reaction can be used with alkenyl stannanes, alkenyl halides, and triflates, 196 733
and the reactions occur with retention of configuration at both the halide and stannane.
SECTION 8.2
These methods are applicable to stereospecific syntheses of materials such as the
retinoids. 197 Reactions Involving
Organopalladium
Intermediates
2.5 mol % Pd 2 (dba) 3
CO 2 C 2 H 5
SnBu 3 18.7 mol % AsPh 3
CO 2 C 2 H 5
+
I NMP
97%
Carotene has been synthesized from a symmetrical 1,10-bis-(tri-n-butyl stannyl)
decapentaene. 198

PdCl (PhCN)
2
I SnBu i Pr NEt 2
2
+ Bu Sn 3 THF/DMF
3
25°C

73%

The versatility of Pd-catalyzed coupling of stannanes has been extended by the demon-
stration that alkenyl triflates are also reactive. 199

H
CH
OSO CF 3 (CH 3 3 H 3 Si(CH 3 ) 3
) Sn
2
CH 3 Pd(PPh ) C
C C 3 4 C
+
H Si(CH ) H
3 3
The alkenyl triflates can be prepared from ketones, 200 and methods are available for
regioselective preparation of alkenyl triflates from unsymmetrical ketones. 201
O
OSO CF 3
2
CH 3
1) LDA CH 3
2) (CF SO ) NPh
2 2
3
The coupling reaction can tolerate a number of functional groups, as illustrated
by a step in the synthesis of the antibiotic nisamycin.

196
W. J. Scott and J. K. Stille, J. Am. Chem. Soc., 108, 3033 (1986).
197 B. Dominguez, B. Iglesias, and A. R. de Lera, Tetrahedron, 55, 15071 (1999).
198 B. Vaz, R. Alvarez, and A. R. de Lera, J. Org. Chem., 67, 5040 (2002).
199
W. J. Scott, G. T. Crisp, and J. K. Stille, J. Am. Chem. Soc., 106, 4630 (1984); W. J. Scott and
J. E. McMurry, Acc. Chem. Res., 21, 47 (1988).
200 P. J. Stang, M. Hanack, and L. R. Subramanian, Synthesis, 85 (1982).
201
J. E. McMurry and W. J. Scott, Tetrahedron Lett., 24, 979 (1983).