Electrochemically promoted tandem cyclization of functionalized methylenecyclopropanes: synthesis of tetracyclic benzazepine derivatives

In this study, an electrocatalytic tandem cyclization reaction of amide-tethered methylenecyclopropanes has been developed, which can realize the rapid construction of tetracyclic benzazepine derivatives in moderate yields with good functional group compatibility under relatively mild conditions. In this transformation, the catalytic amount of ferrocene serves as the electrocatalytic medium, and electron transfer on electrodes can replace oxidants or reducing agents, which is more environmentally friendly than and economically comparable to traditional photocatalysis or metal catalysis. Moreover, the origin of the regiochemistry is well elucidated through density functional theory (DFT) calculations.