Photoinduced tandem radical cyclization/heteroarylation of N-allylbromodifluoroacetamides with quinoxalin-2(1H)-ones or coumarins under metal- and photocatalyst-free conditions

Abstract

A visible-light-promoted tandem radical intramolecular 5-exo-trig cyclization/heteroarylation between N-allyl-2-bromo-2,2-difluoroacetamides and quinoxalin-2(1H)-ones or coumarins has been developed without an external photocatalyst. By applying this new approach, a broad range of valuable α,α-difluoro-γ-lactam-fused quinoxalin-2(1H)-ones and coumarins (49 examples) can be facilely obtained at room temperature, thus showing the wide utility of this protocol. Moreover, mechanistic experiments reveal the involvement of an electron donor–acceptor (EDA) complex in this transformation.