Electron Donor-Acceptor Complex Enabled Cyclization/Sulfonylation Cascade of -Heterocycles with Thianthrenium Salts.

We report a visible-light-promoted cyclization/sulfonylation cascade of -heterocycles with thianthrenium salts using DABSO as the SO surrogate. This method features excellent functional group tolerance, wide substrate scope, and late-stage elaboration of bioactive relevant molecules. Mechanistic investigations reveal that the photoactive electron donor-acceptor (EDA) complexes between thianthrenium salts and DABCO are capable of the generation of aryl radicals, which induce the following SO insertion by attacking DABSO, thus triggering the key radical cyclization step.