I₂-Catalyzed/Mediated C−S and C−I Bond Formation: Solvent- and Metal-Free Approach for the Synthesis of β-Keto Sulfones and Branched Sulfones

Herein, we report a solvent- and transition-metal-free, iodine-catalyzed formation of C−S (sulfone) bonds for the synthesis of β-keto sulfones using readily accessible methyl ketones and sulfonyl hydrazides. This study also features the α-functionalization of β-keto sulfones to synthesize β-keto thiosulfones and α-iodo-β-keto sulfones via iodine-catalyzed carbon-sulfide (C−S) bond formation under solvent-free conditions and iodine-mediated C−I bond formation under aqueous conditions, respectively. The analytical studies and control experiments allow insights into a free-radical coupling strategy. Overall, the presented protocol is operationally simple and scalable, has a broad range of functional group tolerance, and provides access to three functionalized organic scaffolds. (Figure presented.).