Photoredox-Catalyzed Cascade Radical Cyclization of Ester Arylpropiolates with CF3SO2Cl To Construct 3‑Trifluoromethyl Coumarin Derivatives

We report a highly efficient method to construct 3-trifluoromethyl coumarins using CF3SO2Cl 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.