Highly diastereoselective synthesis of (E)-1-(trimethylsilyl)-1-en-3-ynes, and (1E,3Z)- and (1E,3E)-1-(trimethylsilyl)-1,3-dienes

In the stereospecific palladium-catalysed cross-coupling reaction of 1-alkynylzinc chlorides or (E)-1-alkenyl diisobutylalanes, (E)-2-bromovinyltrimethylsilane reacts preferentially, in the presence of the corresponding (Z) -stereoisomer to afford good yields of (E)-1-trimethylsilyl-1-en-3-ynes (4) or (1E, 3E)-1-trimethylsilyl -1,3-dienes (6), respectively, having very high stereoisomeric purities. Compounds 4 are easily converted into (1E, 3Z) -1-trimethylsilyl-1,3-dienes (5) by selective hydrometallation reactions, followed by protonolysis.