Palladium-catalyzed diastereoselective syntheses of (E)-1-trimethylsilyl-2-alkenes, (E)-1-trimethylsilyl-1-alken-3-ynes, (1E,5E)-1-trimethylsilyl-1,5-alkadien-3-ynes, (1E,3Z)- and (1E,3E)-1-trimethylsilyl-1,3-alkadienes

Abstract On the basis of our observation that (E)-1-bromo-1-alkenes undergo preferentially stereospecific Pd-catalyzed cross-couplings with a variety of organometallics, in the presence of the corresponding (Z)-stereoisomers, efficient and convenient diastereoselective procedures have been developed to prepare nearly stereoisomerically pure (E)-1-trimethylsilyl-2-alkenes ( 4 ), (E)-1-trimethylsilyl-1-alken-3-ynes ( 5 ), (1E,5E)-1-trimethylsilyl-1,5-alkadien-3-ynes ( 6 ), and (1E,3E)-1-trimethylsilyl-1,3-alkadienes ( 8 ) from stereoisomeric mixtures of alkenyl bromides. Compounds 5 have been stereoselectively converted into (1E,3Z)-1-trimethylsilyl-1,3-dienes ( 7 ) by selective hydrometallations, followed by hydrolysis. Some synthetic applications of compounds 5–8 have been also examined.