Copper-Catalyzed Selective Aerobic Oxidative Cascade Reaction of Hydrazines, DABSO, and Amines for the Direct Synthesis of Sulfonamides

A Cu-catalyzed highly selective aerobic oxidative coupling reaction of hydrazines and amines has been achieved with the use of 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) as a sulfonyl group source. The hydrazines were explored as aryl precursors for the coupling reaction with DABSO, which directly reacted with amines without use of any additional additives. The cascade reaction was performed under mild conditions and tolerated a wide range of substrates affording the corresponding sulfonamides with good chemical yields. This conceptually new method proceeds with the release of nitrogen, providing an easy and practical strategy for the preparation of sulfonamides.