Photoredox-Catalyzed Cascade Radical Cyclization of Ester Arylpropiolates with CF3SO2CI To Construct 3-Trifluoromethyl Coumarin Derivatives

We report a highly efficient method to construct 3-trifluoromethyl coumarins using CF(3)SO(2)C1 as the trifluoromethyl radical source with ester 3-arylpropiolates. The reaction incorporated a cascade cyclization/dearomatization/ester migration/oxidization/rearomatization process to afford various 3-trifluoromethyl coumarins under visible light irradiation in good to excellent yields.