Ir-Catalyzed Enantioselective, Intramolecular Silylation of Methyl C-H Bonds

We report highly enantioselective infra molecular, silylations of unactivated, primary C(sp(3))-H bonds. The reactions form dihydrobenzosiloles in high yields with excellent enantioselectivities by functionalization of enantiotopic methyl groups under mild conditions. The reaction is catalyzed by an iridium complex generated from [Ir(COD)OMe](2) and chiral dinitrogen ligands that we recently disclosed. The C Si bonds in the enantio-enriched dihydrobenzosiloles were further transformed to C-Cl, C-Br, C-I, and C-O bonds in final products. The potential of this reaction was illustrated by sequential C(sp(3))-H andC(sp(2))-H silylations and functionalizations, as well as diastereoselective C-H silylations of a chiral, natural-product derivative containing multiple types of C-H bonds. Preliminary mechanistic studies suggest that C-H cleavage is the rate-determining step.