Enantioselective Cobalt-Catalyzed Cascade Hydrosilylation and Hydroboration of Alkynes to Access Enantioenriched 1,1-Silylboryl Alkanes

Enantioenriched 1,1-silylboryl alkanes possess silyl and boryl groups that are both connected to the same stereogenic carbon center at well-defined orientations. As these chiral multifunctionalized compounds potentially offer two synthetic handles, they are highly valued building blocks in asymmetric synthesis as well as medicinal chemistry. Despite the potential usefulness, efficient synthetic approaches for their preparation are scarce. Seeking to address this deficiency, an enantioselective cobalt-catalyzed hydrosilylation/hydroboration cascade of terminal alkynes has been realized. This protocol constitutes an impressive case of chemo-, regio-, and stereoselectivity wherein the two different hydrofunctionalization events are exquisitely controlled by a single set of metal catalyst and ligand, an operation which would usually require two separate catalytic systems. Downstream transformations of enantioenriched 1,1-silyboryl alkanes led to various valuable chiral compounds. Mechanistic studies suggest that the present reaction undergoes highly regioselective and stereocontrolled sequential hydrosilylation and hydroboration processes.

Automated summary

Enantioenriched 1,1-silylboryl alkanes are valuable chiral multifunctional compounds, serving as important building blocks in asymmetric synthesis and medicinal chemistry. A cobalt-catalyzed hydrosilylation/hydroboration cascade has been developed for the efficient synthesis of these compounds, exhibiting impressive levels of selectivity and control in the hydrofunctionalization processes.