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

The enantioselective intermolecular sp(3) C-H functionalization at the allylic and benzylic positions was achieved using rhodium-catalyzed reactions with 4-phenyl-N-(rnethanesulfonyl)-1,2,3-triazole. The optimum dirhodium tetracarboxylate catalyst for these reactions was Rh-2(S-NTTL)(4). The rhodium-bound a-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 sp(3) C-H bonds of substrates containing additional functionality.