Photoinduced EDA-complex-mediated late-stage C-H iodination of arenes using aryldibenzothiophenium salts under air.

We report a visible-light-driven, metal-free iodination of arenes using aryldibenzothiophenium (Ar-DBT) salts and potassium iodide. This transformation operates efficiently under air with KI as the optimized iodide source, forming an electron donor-acceptor (EDA) complex that generates aryl radicals upon visible-light irradiation. This protocol exhibits broad functional group tolerance across electronically diverse arenes, heterocycles, and sterically congested substrates. Notably, the synthetic utility of this protocol is demonstrated through the late-stage diversification of a wide array of structurally complex bioactive, agrochemical molecules, and functional molecules, as well as the efficient synthesis of dihalogenated xantphos derivatives.