Synthesis of thiazoles and imidazoles from isothiocyanates and tosylmethyl isocyanide. Base‐induced ring transformation of 5‐amino‐1,3‐thiazoles to imidazole‐5‐thiols

Abstract
Base‐induced cycloadditions of tosylmethyl isocyanide to a series of isothiocyanates have been investigated. Depending on the reaction conditions, thiazoles 5 and/or imidazoles 7 are obtained, with the thiazoles, in particular, being obtained with high regiospecificity. During the course of this work a high‐yield ring transformation of 5‐amino‐1,3‐thiazoles (5) to imidazole‐5‐thiols (7) was discovered, which has not been previously reported. A number of reactions of 7 are described.