Cobalt-Catalyzed Z-Selective Hydrosilylation of Terminal Alkynes

A cobalt-catalyzed Z-selective hydrosilylation of alkynes has been developed relying on catalysts generated from bench-stable Co(OAc)2 and pyridine-2,6-diimine (PDI) ligands. A variety of functionalized aromatic and aliphatic alkynes undergo this transformation, yielding Z-vinylsilanes in high yields with excellent selectivities (Z/E ratio ranges from 90:10 to >99:1). The addition of a catalytic amount of phenol effectively suppressed the Z/E-isomerization of the Z-vinylsilanes that formed under catalytic conditions.