Phosphine-Catalyzed Visible-Light-Induced Aminodifluoroalkylation of Alkenes: Access to α,α-Difluoro-γ-lactams

A visible-light-induced, phosphine-catalyzed radical cyclization of α-bromodifluoroacetamides with various olefins has been established for the efficient synthesis of α,α-difluoro-γ-lactams. This protocol offers mild reaction conditions and excellent functional-group compatibility and delivers the desired lactam products in moderate to good yields, even on a gram scale. Mechanistic studies support a nonchain radical pathway, which involves the formation of a dppb-Br electron donor-acceptor complex, followed by radical addition and intramolecular cyclization. This work presents a practical and environmentally friendly strategy for the construction of valuable fluorinated lactam frameworks.