Iodide-Induced Reductive Radical Generation from Sulfonyl Diazonium Salts: A Metal-Free Iodosulfonylation of Alkynes for (E)-β-Iodovinyl Sulfones Synthesis.

A metal-free halosulfonylation of alkynes using sulfonamides and tBuONO enables (E)-β-halovinyl sulfone synthesis. Control experiments and DFT calculations support a sulfonyl radical mechanism involving SET between diazonium intermediates and the iodide anion. This tandem process achieves high yields, broad scope, and exclusive E-selectivity under mild conditions, providing direct access to vinyl sulfones without prefunctionalization of sulfonamides.