Copper-Catalyzed Formal Dihydrosilylation of Terminal Alkynes: A C(sp)–H Silylation-Hydrosilylation-Hydrogenation Sequence

Copper-catalyzed regioselective double anti-Markovnikov
hydrosilylation of terminal alkynes has been developed by employing
a copper catalyst generated from readily available CuOAc and 1,3-bis­(diphenylphosphino)­propane
(dppp). A wide range of alkyl- and arylacetylenes undergo this dihydrosilylation
reaction to afford gem-disilylalkanes in high isolated
yields with high selectivity. Mechanistic studies, including identification
and isolation of reactive intermediates, control experiments, deuterium-labeling
reactions, and stoichiometric organometallic reactions, reveal that
this copper-catalyzed formal dihydrosilylation of terminal alkynes
proceeds through a reaction sequence combining C­(sp)–H silylation
of alkynes to form alkynylsilanes, hydrosilylation of alkynylsilanes
to provide gem-disilylalkenes, and hydrogenation
of gem-disilylalkenes to afford gem-disilylalkanes. Both copper hydride and copper acetylide species
are key active intermediates for this copper-catalyzed dihydrosilylation
process.

通过利用易得的CuOAc和1,3-双(二苯基膦基)丙烷（dppp）制备的铜催化剂，已开发出对末端炔烃进行区域选择性双反Markovnikov加氢硅烷化反应。多种烷基和芳基炔烃在此二氢硅烷化反应中转化，以高孤立产率和高度选择性得到Gem-二硅烷基烷烃。机理研究表明，包括活性中间体的鉴定和分离、控制实验、氘标记反应和当量有机金属反应等，均表明此铜催化的末端炔烃形式二氢硅烷化反应通过结合炔烃的C(sp)–H硅烷化形成炔基硅烷、炔基硅烷的氢硅烷化生成Gem-二硅烷基烯烃以及Gem-二硅烷基烯烃的氢化来提供Gem-二硅烷基烷烃。铜氢和铜乙炔物种是该铜催化二氢硅烷化过程中的关键活性中间体。