Direct α-Sulfenylated Carbonyl Compound Synthesis from Vinyl Boronates via Molybdenum-Catalyzed Oxidative Cascade Reaction

We herein report that a Mo-based catalyst can effectively promote the regioselective syntheses of α-sulfenylated ketones and α-sulfenylated aldehydes from widely accessible vinylboronic esters with thiols. Distinct from traditional methods in the synthesis of α-sulfenylated carbonyl compounds with reactive precursors or strong oxidants, this protocol utilizes unactivated vinylboronic esters as starting materials and sustainable air (O₂) as the oxidant. This method features operationally simple, green solvents, cost-effective reagents, and good functional group compatibility. Moreover, the synthetic value of this protocol is demonstrated on gram-scale reaction and late-stage transformation of products. Mechanistic studies reveal that the molybdenum catalyst undergoes the single-electron transfer process with a thiol to generate a thiyl radical, and the α-boro-alkyl radical intermediate trapped by O₂ drives the oxidative deboronation.