An efficient synthesis of 2-thio-5-amino substituted benzoquinones via KI catalyzed cascade oxidation/Michael addition/oxidation starting from hydroquinone

Abstract

A simple and efficient synthesis of 2-thio-5-amino substituted benzoquinones via KI catalyzed cascade oxidation/S-Michael addition/oxidation/N-Michael addition/oxidation starting from hydroquinone, amines and S-alkylisothiouronium salts was described. Various 2-thio-5-amino substituted benzoquinones were obtained by this method in moderate to good yields. The use of S-alkylisothiouronium salts as thiol equivalents is more convenient and environmental friendly.