KI-catalyzed C–S bond formation via an oxidation relay strategy: efficient access to various α-thio-β-dicarbonyl compounds

Abstract

An efficient and practical methodology to obtain α-thio-β-dicarbonyl compounds was presented under alkaline conditions via potassium iodide (KI) catalysis; various symmetrical/unsymmetrical 1,3-dicarbonyl compounds were obtained under an aerobic atmosphere in moderate to excellent yields, with good functional group tolerance. Notably, a widely used anti-inflammatory drug butazodine could be modified with our protocol, even on a gram scale.

Recent Advances in Iodine‐Promoted C−S/N−S Bonds Formation

“…Following our continuous interests on organosulfur chemistry, [108][109][110][111][112][113] we disclosed aK I-promoted CÀSb ond formation for the synthesis of various a-thiob-dicarbonyl compounds 139 (Scheme44). [114] Compared with previouss tudies, the reactionu sed oxygen as the green terminal oxidant to recycle iodine and possessed relativelyb road substrate scope, including diverse symmetrical/unsymmetrical methylene substituted 1,3-diketones 138.W hen TEMPOo rB HT was added to the reaction, the desired products were detected in ar elatively good yield, whichs uggested that ar adicalp rocess couldb er ule out. By the detailed mechanism studies, halide was oxidized to trace amountso fh alogen( Br 2 andI 2 ), which was attacked by an ucleophilic sulfur atom of thiols/disulfide to form aS ÀX( Br and I) bond, triggering the umpolung reactivity of the sulfur and halide atom.…”

“…Accordingly, based on our previous works, we conceptually named the recycle process of iodine as the "oxidation relay strategy". [114] It should be mentioned that this strategy has widespread applicationi nt he synthesis of CÀS/NÀSb onds containing compounds and has made great contributiontot he development of this domain.…”

“…Following our continuous interests on organosulfur chemistry, [108–113] we disclosed a KI‐promoted C−S bond formation for the synthesis of various α‐thio‐β‐dicarbonyl compounds 139 (Scheme 44). [114] Compared with previous studies, the reaction used oxygen as the green terminal oxidant to recycle iodine and possessed relatively broad substrate scope, including diverse symmetrical/unsymmetrical methylene substituted 1,3‐diketones 138 . When TEMPO or BHT was added to the reaction, the desired products were detected in a relatively good yield, which suggested that a radical process could be rule out.…”

“…By the detailed mechanism studies, halide was oxidized to trace amounts of halogen (Br 2 and I 2 ), which was attacked by a nucleophilic sulfur atom of thiols/disulfide to form a S−X (Br and I) bond, triggering the umpolung reactivity of the sulfur and halide atom. Accordingly, based on our previous works, we conceptually named the recycle process of iodine as the “oxidation relay strategy” [114] . It should be mentioned that this strategy has widespread application in the synthesis of C−S/N−S bonds containing compounds and has made great contribution to the development of this domain.…”

Visible‐Light Cercosporin Catalyzed Sulfenylation of Electron‐Rich Compounds with Thiols under Transition‐Metal‐Free Conditions

“…Notably many of these transformations took place under the mild conditions of visible light photocatalysis . Lei and Zhu reported oxidative coupling from 1,3‐diketones/cyclic ketones and β‐dicarbonyl thioethers/α‐thio‐β‐dicarbonyl compounds to generate C−S bond. Recently Huang and group has developed method which describes the α‐aryl thiolation via organophotoredox catalysis of ketones .…”