Synthesis of Substituted Alkenes by 2-Electron Reduction of Acetylenes

摘要

Unsymmetrical diyne,7-tert-butyldimethylsilyl-4,6-heptadiynyl methyl ether la was site-selectively reduced to 7-tert-butyldimethylsilylhept-4-en-6-ynyl methyl ether 2a by two equivalents of lithium 4,4'-di-tert-butylbiphenylide(LDBB).Produced dilithio-intermediate,after transmetalation to diethylzinc,reacted with two kinds of electrophiles regio-and stereoselectively in a stepwise manner to give substituted 1,3-enynes.