A new method for the formation of γ- and δ-lactones from carboxylic acids through direct conversion of benzylic C–H to C–O bonds is described. The reaction is conveniently induced by visible light and relies on a mild cooperative catalysis by the combination of molecular iodine and an organic dye.
Cooperative iodine and photoredox catalysis for direct oxidative lactonization of carboxylic acids
Chem. Commun. 2019, 55 (7), 933-936, DOI: 10.1039/C8CC08594C.