Sequential Catalytic Annulations: Divergent Synthesis of Heterocycles through a Radical [1,4]-Oxygen Shift.

A radical [1,4]-oxygen-atom transfer has been realized by the reaction of linear alkyne-tethered ketoximes and ethynylbenziodoxolones (EBX) under sequential catalytic conditions. Mechanism studies indicate that the O atom transfer experiences a cascade O atom radical cyclization/alkynylation/N-O bond photocleavage and subsequent N,O-diradical rearrangement. By the diversification of catalytic sequences, a series of structurally important 3-pyrrol-3-ones and chlorinated furo[3,2-]pyrroles are divergently synthesized along with an O atom shift under the catalysis of Cu/Ir photosensitization and Cu/Ir photosensitization/AlCl, respectively.