Copper-Catalyzed Radical Sulfonylation: Divergent Construction of C(sp)-Sulfonyl Bonds with Sulfonylhydrazones.

Sulfonylhydrazones have been proven to be versatile synthetic intermediates in a panel of transformations. However, radical sulfonylation with sulfonylhydrazone as sulfonyl radical source is relatively rare. Here, we found that sulfonylhydrazone can serve as a new sulfonyl radical precursor to couple various partners such as arylacetic acids, ene-yne-ketones, and -quinone methides under copper catalysis and microwave irradiation. The reactions of sulfonyl radicals have been successively developed to enable the divergent synthesis of C()-sulfonyl bonds. In addition, when alkynes and alkenes are used as radical receptors, this method can also promote the formation of C()-sulfonyl bonds. This finding suggests that sulfonylhydrazone could be regarded as a potentially useful sulfonyl radical in sulfone synthesis.