Water-Mediated Electrochemical Sulfonylation of Alkynes: Switchable Access to Alkynyl versus Alkenyl Sulfones.

A novel electrochemical oxidative sulfonylation method has been established for the selective, sustainable synthesis of alkynyl and alkenyl sulfones from alkynes and thiophenols. In this method, water serves as both the hydrogen and oxygen sources, while the current intensity and the water dosage can be readily tuned to control the reaction outcome. Importantly, the transformation proceeds under mild conditions without the use of metal catalysts or hazardous oxidants. The protocol also exhibits broad substrate scope and excellent functional-group compatibility. Mechanistic investigations support a radical-mediated pathway, and the practical utility of the method was further demonstrated by gram-scale synthesis.