Bis(phosphine)cobalt-Catalyzed Highly Regio- and Stereoselective Hydrosilylation of 1,3-Diynes

Seven bis(phosphine) cobalt complexes and one tris(phosphine) cobalt complex were tested for hydrosilylation of 1,3-diynes, among which dppp-CoCl2 (1 mol %) exhibited the best regio- and stereoselectivity, affording (E)-2-silyl-1,3-enynes through monohydrosilylation at the internal carbon of the 1,3-diyne unit via syn addition. Good functional tolerance was achieved, 32 substrates were tested, and the reactions could be readily amplified to a gram level. For most of the substrates, the transformation could be completed in 5 min at room temperature. To date, this is the most effective base-metal-catalyzed system for the selective hydrosilylation of 1,3-diynes.