Pd-Catalyzed Selective Synthesis of Cyclic Sulfonamides and Sulfinamides Using K₂S₂O₅ as a Sulfur Dioxide Surrogate

A variety of cyclic sulfonamides and sulfinamides could be selectively synthesized under Pd catalysis using haloarenes bearing amino groups and a sulfur dioxide (SO₂) surrogate. The amount of base was key in determining the selectivity. Mechanistic studies revealed that sulfinamides were initially formed via an unprecedented formal insertion of sulfur monoxide and were oxidized to sulfonamides in the presence of an iodide ion and DMSO.