Vinyl Sulfonium Salts as the Radical Acceptor for Metal-Free Decarboxylative Alkenylation.

Vinyl sulfonium salts typically act as an electrophilic Michael acceptor, thus initiating many tandem cyclization reactions. Herein, we disclosed the novel reactivity of vinyl sulfonium salts as a radical acceptor. Using redox-active ester as an alkyl radical precursor, metal-free decarboxylative alkenylation with vinyl sulfonium salts was realized using eosin Y as a photocatalyst. This process features a broad substrate scope and tolerates with a broad range of primary, secondary, tertiary carboxylic acids.