Mechanism and Origins of Enantioselectivity of Iridium-Catalyzed Intramolecular Silylation of Unactivated C(sp3)-H Bonds.

Density functional theory calculations were performed to investigate the iridium-catalyzed intramolecular silylation of unactivated C(sp3)-H bonds. The computations show that the in situ generated iridium(III) silyl dihydride species is the active catalyst, from which the followed migratory insertion and the transmetalation would generate the iridium(III) disilyl hydride species. The reaction was found to take place through an Ir(III)/Ir(V) catalytic cycle, and the C(sp3)-H bond oxidative addition constitutes the rate- and enantioselectivity-determining step. The steric repulsion and C-H···π interaction were found to account for the experimentally observed enantioselectivity.