Facile cyclization of amidyl radicals generated from N-acyltriazenes

N-Acyltriazenes serve as a tin-free and initiator-free source for amidyl radicals. Thermal decomposition of N,N′-diaryl-N-(4-pentenoyl)triazenes in refluxing toluene led to the formation of monocyclic and tricyclic lactams in satisfactory yields via 5-exo amidyl radical cyclization.