A SELECTIVE SYNTHESIS OF (E)-VINYLSILANES BY CATIONIC RHODIUM COMPLEX-CATALYZED HYDROSILYLATION OF 1-ALKYNES AND TANDEM HYDROSILYLATION ISOMERIZATION REACTION OF PROPARGYLIC ALCOHOLS TO BETA-SILYL KETONES

(E)-Vinylsilanes were obtained with high selectivities by [Rh(COD)(2)]BF4/2PPh(3)-catalyzed hydrosilylation of 1-alkynes with triethylsilane. A wide range of 1-alkynes were used. The hydrosilylation of propargylic alcohols with triethylsilane gave (E)-gamma-silyl allylic alcohols 2h-r, a useful source of a chiral alcohol, with high selectivities in excellent yields. The reaction can be carried out without protecting the alcohol functionality. The resulting (E)-gamma-silyl allylic alcohols could be transformed into beta-silyl ketones. The isomerization was also catalyzed by [Rh(COD)(2)]BF4/2PPh(3). Furthermore, the tandem hydrosilylation-isomerization of secondary propargylic alcohols could be carried out in a one-pot procedure.