Pd-Catalyzed Regio- and Stereoselective Addition of Boronic Acids to Silylacetylenes: A Stereodivergent Assembly of β,β-Disubstituted Alkenylsilanes and Alkenyl Halides

An
efficient Pd-catalyzed addition of boronic acids to silylacetylenes
is described, providing β,β-disubstituted (E)- or (Z)-alkenylsilanes in satisfactory yields
with excellent regio- and stereoselectivity under mild reaction conditions.
It represents the first highly regio- and stereoselective addition
of boronic acids to aryl and alkenyl silylacetylenes. Moreover, the
sequential Pd-catalyzed boron addition/N-halosuccinimide-mediated
halodesilylation reaction results in a stereodivergent approach to
β,β-disubstituted alkenyl halides, which can serve as
versatile synthetic intermediates for the stereodivergent assembly
of (E)- and (Z)-trisubstituted alkenes
via transition-metal-catalyzed cross-coupling reactions.