Zn-promoted Sandmeyer-type reductive chalcogenation of (hetero)aryl diazonium salts†

In this report, we describe a nickel-free, zinc-induced reductive coupling between (hetero)aryl diazonium salts and electrophilic chalcogen species under mild reaction conditions. This nonbasic protocol offers excellent chemoselectivity and substrate tolerance, yielding a broad spectrum of unsymmetrical diaryl and aryl–alkyl chalcogenides with good to excellent yields. Moreover, scale-up reactions, late-stage modifications of bioactive molecules and versatile product derivations have been conducted to showcase the practicality of this system. Preliminary mechanistic studies suggest the involvement of a single-electron transfer (SET) process from zinc to diazonium salts or the formation of zinc thiolate via oxidative addition of S–S bonds, revealing the versatile roles of zinc in this Sandmeyer-type sulfuration, which has been rarely studied.