Photocatalytic Synthesis of 1,2-Sulfinate-Sulfonate Esters by Four-Component Radical-Polar Crossover Cyclization

Structurally diverse 1,2-sulfinate-sulfonate esters are shown to be conveniently prepared through visible light-induced sulfonation and sulfinylation of difunctionalized alkenes using alcohols and NaHSO3. The reactions proceed under mild conditions in the presence of photocatalysts and HCO2H as an additive, exhibiting good functional group tolerance and a broad scope. Furthermore, this method is scalable and has been successfully applied to synthesize 1,2-disulfonic acid esters. A plausible mechanistic pathway has been proposed based on control experiments.