Cu(I)-Photosensitizer-Catalyzed Olefin-α-Amino Radical Metathesis/Demethylenative Cyclization of 1,7-Enynes.

A demethylenative En-Yne radical cyclization of 1,7-enynes has been successfully developed to chemoselectively afford 3,4-dihyroquinolin-2-ones or quinolin-2-ones under the catalysis of Cu(I) photosensitizers PS3 and PS6 with different redox potentials. The preliminary mechanistic experiments revealed that the reaction underwent an unprecedented olefin-α-amino radical metathesis-type process. A reasonable mechanism was proposed to illustrate the catalyst-controlled chemoselectivity of the reaction based on preliminary mechanistic experiments and DFT calculations.