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

A metal-free halosulfonylation of alkynes using sulfonamides and ^<i>t</i>BuONO enables (<i>E</i>)-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 <i>E</i>-selectivity under mild conditions, providing direct access to vinyl sulfones without prefunctionalization of sulfonamides.