Enantioselective Synthesis of Silicon-Stereogenic Monohydrosilanes by Rhodium-Catalyzed Intramolecular Hydrosilylation

Enantiopure monohydrosilanes are versatile chiral reagents for alcohol resolution and mechanistic investigation. Herein, we have demonstrated the asymmetric synthesis of monohydrosilanes via an intramolecular hydrosilylation strategy. This protocol is suitable for the synthesis of five- and six-membered cyclic monohydrosilanes, including a class of chiral oxa-silacycles, with excellent diastereoselectivities, regioselectivities, and enantioselectivities.  Notably, the catalyst loading could be reduced to 0.1 mol% which represents one of the most efficient method to access chiral monohydrosilanes. Mechanistic studies and DFT calculation indicate this Rh-catalyzed intramolecular asymmetric hydrosilylation reaction might undergo a Chalk-Harrod mechanism, and the enantio-determining step was predicted to be oxidative addition of Si-H bond.