TBADT-Photocatalyzed Trifluoromethylation of Phenylpropiolamides Using Langlois Reagent: Access to Oxindole Derivatives

In this study, we report the radical-mediated trifluoromethylation of phenylpropiolamides using the Langlois reagent (CF₃SO₂Na) under ultraviolet light irradiation, with tetrabutylammonium decatungstate (TBADT) serving as an efficient inorganic photocatalyst. This method synthesizes a wide range of oxindoles by generating a CF₃ radical, which induces an intermolecular C-CF₃ bond (via a Michael addition on the propiolamide moiety), followed by an intramolecular C-C bond formation and reduction sequence. Thus, a broad range of trifluoromethyl-substituted oxindoles have been accomplished in high yields under mild conditions.