Selective Synthesis of Multisubstituted Olefins Utilizing <i>gem</i>- and <i>vic</i>-Diborylated Vinylsilanes Prepared by Silylborylation of an Alkynylboronate and Diborylation of Alkynylsilanes

The synthesis of a series of <i>gem</i>- and <i>vic</i>-diborylated vinylsilanes was accomplished via highly selective transition-metal-catalyzed <i>syn</i>-dimetalation to the alkynylmetal species. This protocol served as a general synthetic method toward regio- and stereodefined multisubstituted olefins. The key steps are the diastereoselective Suzuki–Miyaura cross-coupling reactions of <i>gem</i>- and <i>vic</i>-diborylated vinylsilanes, in which the two boron groups showed discrete reactivities to afford diverse precursors of multisubstituted olefins