Pincer cobalt complex-catalyzed Z-selective hydrosilylation of terminal alkynes

A phosphine-iminopyridine ((PNN)-N-C) cobalt-catalyzed Z-selective hydrosilylation of terminal alkynes with Ph2SiH2 has been developed for the synthesis of (Z)-beta-vinylsilanes with high regio- and stereoselectivity and wide functional group tolerance. Furthermore, the Co-catalyzed hydrosilylations of unsymmetrical arylalkyl disubstituted internal alkynes afford syn-addition products with unique regioselectivity: the silyl group is added to the alkyl-substituted carbon, instead of the aryl-substituted carbon. The (Z)-beta-vinylsilane products are further applied to Pd-catalyzed Hiyama-Denmark cross-couplings for stereoselective synthesis of (Z)-disubstituted alkenes.