Mechanistic and experimental study on copper-catalyzed C3-sulfenylation of indoles with sulfur powder and aryl iodides

Abstract

The copper-catalyzed sulfenylation of indoles with aryl iodide and sulfur powder has been investigated both experimentally and theoretically. This protocol provides a direct and facile approach to prepare 3-sulfenylindoles with moderate to excellent yields and good functional-group tolerance. The in-situ IR analysis provided evidence for that NaOAc could promote the synthesis of diphenyl disulfide by the coupling of aryl iodide and sulfur powder. According to DFT calculations, the coupling pathway involving the intermediate N-methyl-3-iodoindole is more favored than the direct coupling by the CH activation of indole. The N-methyl-3-iodoindole was identified as a crucial intermediate in the catalytic cycle.