CO2•– Enabled Synthesis of Phenanthridinones, Oxindoles, Isoindolinones, and Spirolactams

We report herein that photoinduced CO2•– enabled reductive intramolecular radical cyclization of a variety of aryl iodide derivatives to the corresponding phenanthridinone, oxindole, isoindolinone, and spirolactam derivatives in good yields. Preliminary mechanistic studies suggested the generation of CO2•– through homolysis of cesium formate in the presence of light, and the further involvement of CO2•– and the aryl radical was directly proved by trapping with diphenyl styrene and TEMPO.