Copper- and Phosphane-Free Sonogashira Coupling of Arenediazoniumo-Benzenedisulfonimides

Arenediazonium o-benzenedisulfonimides can be used as efficient reagents in Sonogashira coupling reactions. In this work, reactions were carried out in DMSO under very mild conditions (without copper or phosphanes), and gave rise to arylated alkynes in good to excellent yields (25 examples, average yield 83%). o-Benzenedisulfonimide could be recovered from all the reactions in yields of 80%, so it could be recycled for the preparation of other diazonium salts. Mechanistic insights revealed the fundamental roles of DMSO and the anion of o-benzenedisulfonimide in the formation of the catalyst, and also the importance of DMSO in the catalytic cycle.