A mild and fast continuous-flow trifluoromethylation of coumarins with the CF₃ radical derived from CF₃SO₂Na and TBHP

A mild and fast Cu(I)-catalyzed trifluoromethylation of coumarins with CF₃SO₂Na and TBHP in a continuous-flow reactor has been developed. This method is experimentally simple and carried out under mild conditions, affording the corresponding products in moderate to good yields, and showing wide substrate tolerance. The scale-up flow process results in an isolated yield of 68% and a productivity of 305 mg h⁻¹ of 3-trifluoromethyl-7-diethylamino-4-methyl coumarin when the concentration was increased five-fold. Given these features and the widespread applications of coumarins, this method may find use from laboratory to manufacturing.