Nitrene Transfer Radical Relay: A Light-Enabled Strategy for Accessing Tetrahydropyridine.

Nitrene transfer reactions represent one of the key reactions to rapidly construct new carbon-nitrogen bonds. Herein, we report on the application of Cu(acac)2 for the photochemical generation of a copper-bound nitrene intermediate, which is key to access substituted tetrahydropyridines from vinyl cyclopropanes in a (5 + 1) cycloaddition reaction. Experimental and computational studies indicate that the reaction proceeds via the addition of the copper-bound nitrene intermediate to olefin, followed by the ring opening of cyclopropane. The broad applicability of this (5 + 1) cycloaddition is further demonstrated by late-stage functionalization of drug derivatives and downstream transformations of the obtained substituted tetrahydropyridines.