Photoredox Iron-Catalyzed Decarboxylative Radical Cyclization for the Synthesis of Oxindoles and Chroman-4-ones

A sustainable, photocatalytic approach for the synthesis of oxindoles and chroman-4-ones was developed using carboxylate salts as radical precursors and FeCl₃ as a catalyst. The reaction proceeds via a decarboxylative radical cyclization mechanism triggered by ligand-to-metal charge transfer under visible light irradiation, operating efficiently at room temperature. This method demonstrates excellent substrate scope, including the use of various alkyl carboxylates, and functional group tolerance and offers a scalable pathway for gram-scale synthesis, highlighting its practical application.