Elemental sulfur as a sulfuration agent in the copper-catalyzed C–H bond thiolation of electron-deficient arenes

By utilizing elemental sulfur as the thiolation agent and oxidant, a copper-catalyzed direct C–H bond thiolation of electron-deficient arenes was demonstrated. Various electron-deficient arenes were proved to be suitable for this transformation. Preliminary mechanistic studies indicated that this reaction underwent a radical pathway, in which the trisulfur radical anion (S₃˙⁻) might play a vital role. Meanwhile, KIE experiments suggested that C–H bond cleavage was not involved in the rate-determining step.