Metal-free, iodine/DMSO-promoted oxidative C(sp2)–H difunctionalization: synthesis of aminochalcogenylated indoles

Abstract

A metal-free strategy for the oxidative difunctionalization of indole derivatives has been developed using iodine and DMSO as the key reaction components. This protocol enables an environment friendly and efficient oxidative C(sp²)–H coupling reaction between indoles, amines, and diphenyl dichalcogenides under mild conditions. The transformation provides direct access to a variety of aminochalcogenylated indoles through the formation of C(sp²)–N and C(sp²)–S/Se bonds in moderate to good yields. A broad range of indole substrates and diaryl disulfides/diselenides were found to be compatible with the reaction conditions. Notably, morpholine derivatives were identified as the most effective amine partners, while more nucleophilic amines were less suitable under the optimized conditions. Furthermore, sulfoximines were successfully employed as alternative nitrogen sources, highlighting the versatility and synthetic utility of the present methodology. The operational simplicity, avoidance of transition metals and external oxidants, and broad substrate scope make this protocol an attractive approach for the synthesis of biologically relevant aminochalcogenylated indole derivatives.