Ligand Relay Cobalt Catalysis for Vicinal Si,O-Alkanes from Terminal Alkynes

Construction of valuable vicinal Si,O-alkanes, which exhibit potential utility in pharmaceuticals and materials science, has yet to be restricted to prefunctionalized reactants. Plenty of efforts have been made, using alkenes as nonprefunctionalized starting materials. Despite that, methodology starting from easily accessible alkynes has been rarely developed, and vicinal Si,O-alkanes containing Si–H have seldom been explored. Here, we report one-pot two-step cobalt-catalyzed sequential hydrosilylation/hydroxylation of terminal alkynes with commercially available TEMPO and diphenylsilane via ligand relay catalysis, featuring low catalyst loading (1 mol %), mild conditions, and broad substrate scope. The successful execution of the double hydrofunctionalization protocol ensures that the vicinal Si,O-alkanes with characterized Si–H are obtained smoothly in good yields and regioselectivity. The derivatizations of the Si–H bond are also demonstrated, delivering silanol, siloxane, and tetra-substituted silane. The possible mechanism has been proposed based on control experiments and computational studies.