Synthesis of 5-Trimethylsilyl-1,4-enynes from Ethoxy(trimethylsilyl)acetylene and Mono- and Diboron Allylic Compounds

Allylic boranes and diboranes add to ethoxy(trimethylsilyl)acetylene with full rearrangement of the allylic moiety to give a series of new trimethylsilyl-substituted cyclic and acyclic 1,4-enynes and polyenynes with a terminal double bond.