The oxidation of thioureas and related compounds in the presence of pyrroles. The synthesis of S-pyrrolylisothiouronium salts

Abstract

The oxidation of thioureas in the presence of pyrroles by halogens or hydrogen peroxide in acidic conditions gives S-pyrrolylisothiouronium salts in high yield. The mechanism of the reaction is believed to involve oxidation of the thiourea to a sulphenyl halide species which then reacts with the pyrrole in a typical electrophilic substitution. The reaction has been extended to include several thioamides and heterocyclic thiols as well as thiourea.