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.