Cascade cyclization reactions of alkylidenecyclopropanes for the construction of polycyclic lactams and lactones by visible light photoredox catalysis

A visible light photocatalytic cascade cyclization reaction of alkylidenecyclopropanes for the rapid construction of seven- and eight-membered ring-containing polycyclic lactams and lactones has been developed. The process is proposed to proceed through a radical pathway, and the suggested radical intermediate was captured by TEMPO successfully. An intermolecular version of the reaction was also achieved, affording a variety of methyl dialinoacetate products.