Palladium-Catalyzed Aminosulfonylation of ortho-Iodoanilines with the Insertion of Sulfur Dioxide for the Synthesis of 3,4-Dihydro-benzothiadiazine 1,1-Dioxides

A simple and efficient Pd-catalyzed oxidative cyclization system is developed for the chemo- and regioselective synthesis of 3,4-dihydro-benzothiadiazine 1,1-dioxides, which are formed through aminosulfonylation of ortho-iodoanilines with SO2. DABSO is utilized as the source of SO2, and the organic compound O2 acts as an oxidant. This direct C-S, S-N, and C-N functionalization is highly efficient, and broad functional group tolerance is observed, resulting in moderate to excellent yields of 3,4-dihydro-benzothiadiazine 1,1-dioxides. Furthermore, this method is amenable to gram-scale synthesis.