Enantioselective Intermolecular C–H Functionalization of Allylic and Benzylic sp3 C–H Bonds Using N-Sulfonyl-1,2,3-triazoles

The enantioselective intermolecular sp3 C–H functionalization at the allylic and benzylic positions was achieved using rhodium-catalyzed reactions with 4-phenyl-N-(methanesulfonyl)-1,2,3-triazole. The optimum dirhodium tetracarboxylate catalyst for these reactions was Rh2(S-NTTL)4. The rhodium-bound α-imino carbene intermediates preferentially reacted with tertiary over primary C–H bonds in good yields and moderate levels of enantioselectivity (66–82% ee). This work demonstrates that N-sulfonyltriazoles can be applied to the effective C–H functionalization at sp3 C–H bonds of substrates containing additional functionality.