3452
J . A m . Chem. SOC.1989, 1 1 1 , 3452-3454
Scheme IIa
6
a
R= H
' Ch
& R-H
h
R= CH(OEt)CH2Br
R=CH,CH,CN
S R=CN ! l R= CH,CH=CH,
.98 and >95%, respectively. Similarly 11 gave >98% pure 12 in 71% yield. Prolonged reaction times must be avoided, since they led to lower stereoselectivity figures. Throughout this investigation, the ste(9) Tour, J. M.; Negishi, E. J . Am. Chem. SOC.1985, 107, 8289.
0 1989 American Chemical Society
