Iridium-Catalyzed α-C(sp3)–H Borylation of Trialkylhydrosilanes

It is known that trialkylhydrosilanes undergo either Si–H or γ-C–H borylation in the iridium-catalyzed reaction with bis(pinacolato)diboron. We developed α-C–H borylation as a new iridium-catalyzed reaction of trialkylhydrosilanes. The key to changing the reaction mode was the use of 2,2′-bipyridines bearing a methyl group at the 5- or 6-position as ligands for the iridium catalyst. This reaction allows direct access to synthetically useful α-borylated hydrosilanes from readily available trialkylhydrosilanes.