Cobalt-Catalyzed (E)-Selectiveanti-Markovnikov Hydrosilylation of Terminal Alkynes

We report a regioselective and stereoselective hydrosilylation of terminal alkynes with catalysts generated from bench-stable Co(acac)2 and bisphoshpine ligands. The cobalt catalyst precursors are activated by the reaction with hydrosilanes, and air-sensitive activators, such as Grignard reagents or NaBHEt3, are not required for catalyst activation. A wide range of aromatic and aliphatic terminal alkynes underwent this cobalt-catalyzed hydrosilylation, affording the corresponding (E)-vinylsilanes in high yields with high regioselectivity and stereoselectivity. These reactions show good functional group compatibility and can be readily scaled up to gram-scales without using a drybox. Deuterium-labeling experiments suggest a cis-addition of hydrosilanes to alkynes.