Ground solid permanganate oxidative coupling of thiols into symmetrical/unsymmetrical disulfides: selective and improved process

The oxidation of thiols to the symmetrical disulfides by using ground solid potassium permanganate under mild and solvent-free conditions has allowed us to selectively oxidize thiols in the presence of other readily oxidized functional groups such as alcohol, aldehyde, amine and alkene without the risk of producing undesired products via competitive oxidation reactions. Unsymmetrical disulfides have also been obtained in moderate to good yields from the oxidative coupling of mixed thiols. Furthermore, ultrasound or microwave irradiation is able to shorten the reaction time compared to conventional stirring in case of the oxidation of sterically demanding alkanethiols or arenethiols.