Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins

In view of generating trisubstituted vinylic chalcogen derivatives, beta-chalcogeno alkenylboranes generated through the chalcogen electrophile induced rearrangements of 1-alkynyltrialkyl borates have been subjected to Suzuki-Miyaura coupling and to boron to copper transmetalation followed by alkylation. Some of the trisubstituted vinyl sulfides obtained by this latter strategy have been converted efficiently into the title olefins through the NiCl2(dmpe) catalyzed coupling with various Grignard reagents. (C) 2003 Published by Elsevier Ltd.