A Convenient Access to DihydroxybenzenethiolsviaReduction ofIso-Thiouronium Salts with Sodium Borohydride

An improved procedure for the prepn. of unstable dihydroxybenzenethiols I (r = H, Me, CH2CH2NH2) and II in 94-99% yields involves mild redn. of the corresponding iso-thiouronium salts, e.g., III, with NaBH4.