Cobalt-Catalyzed Sequential Site- and Stereoselective Hydrosilylation of 1,3- and 1,4-Enynes

Catalytic sequential hydrosilylation of 1,3-enynes and 1,4-enynes promoted by cobalt complexes derived from bisphosphines are presented. Site- and stereoselective Si-H addition of primary silanes to 1,3-enynes followed by sequential intramolecular diastereo- and enantioselective Si-H addition afforded enantioenriched cyclic alkenylsilanes with simultaneous construction of a carbon-stereogenic center and a silicon-stereogenic center. Reactions of 1,4-enynes proceeded through sequential isomerization of the alkene moiety followed by site- and stereoselective hydrosilylation. A wide range of alkenylsilanes were afforded in high efficiency and selectivity. Functionalization of the enantioenriched silanes containing a stereogenic center at silicon delivered a variety of chiral building blocks that are otherwise difficult to access.