Ir-Catalyzed Enantioselective, Intramolecular Silylation of Methyl C–H Bonds
We report highly enantioselective intramolecular, silylations of unactivated, primary C(sp3)–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 enantioenriched 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(sp3)–H and C(sp2)–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.
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