A Multitasking Photoredox-Catalysis for Stereoselective C‒N Bond Formation

A rare photoredox-mediated C‒N bond formation methodology has been developed integrating the concepts of [2+2]-photocycloaddition of styrene in combination with N-centered radical (NCR) generation. Highly significant enamines and imines have been produced in a stereoselective manner using a mild and bench-stable oxime-ester precursor as the N-linchpin. The key attraction is the multitasking catalysis of fac-Ir(ppy)3 involving energy transfer, N-O bond cleavage, N-centered radical generation, imine reduction and cyclobutane ring opening simultaneously in the same reaction pot. Preliminary mechanistic investigations have been performed to have an idea about the mechanism involving both energy transfer mediated cycloaddition and the photoredox mediated iminyl radical generation. Wide functionality tolerance with satisfactory yield and exclusive stereoselectivity are the salient features of this newly discovered methodology.