α‑Diketone Formation Accompanied by Oxidation of Sulfur Functional Group by the Reaction of o‑Alkynylarenesulfoxide with Iodine

The reaction of o-alkynylarenesulfoxide with iodine was investigated in detail, revealing functionalities of the formation of α-diketones with sulfenyl, sulfinyl, and sulfonyl. Additives can change the ratio of products to give medium-to-excellent yields. Results show that water is taken into only sulfonyl compound and that other oxygen atoms constructed in the products are presumably derived from sulfoxide of the starting material and molecular oxygen.