Alkyl Sulfinate Anion-Mediated Hydrosulfonylation of Alkenes/Alkynes via SO2 Insertion: Access to Alkyl Sulfones

An alkyl sulfinate anion-mediated hydrosulfonylation of alkenes/alkynes with alkyl bromides involving SO2 insertion has been developed for the synthesis of alkyl sulfones. Sodium dithionite (Na2S2O4) acts as both an SO2 surrogate and a single-electron donor, thereby obviating the need for metal catalysts or metallic reductants. This protocol features broad substrate scope and high functional group tolerance, accommodating a range of bioactive scaffold molecules such as citronellol, estrone, borneol, and cholesterol. Mechanistic investigations reveal that the alkyl sulfinate anion is a key intermediate, and deuterium-labeling experiments confirm that trace H2O in the solvent serves as the proton source in the protonation step.