Alkylsulfonylation of alkenes involving copper carbene coupling: access to alkyl–alkyl sulfones

Abstract

A novel alkyl radical-initiated alkylsulfonylation of alkenes via copper carbene coupling is developed for the synthesis of various alkyl–alkyl sulfones by employing potassium metabisulphite (K₂S₂O₅) as a connector. In this reaction, readily available K₂S₂O₅ not only serves as a sulfur dioxide source but is also demonstrated to be an efficient reducing agent for promoting the catalytic cycle. Notably, the late-stage modifications of bioactive molecules including estrone and cholesterol derivatives utilizing this protocol could also be achieved. Mechanistic investigations reveal that the transformation involves intramolecular radical cyclization, insertion of “SO₂” and the coupling of copper carbenes in a single reaction step.