Studies on the chemistry of 2,3,5,6‐tetrahydro‐6‐phenylimidazo[2,l‐ b ]‐thiazole. III. . Reaction with isocyanates and isothiocyanates

2,3,5,6‐Tetrahydro‐ b ‐phenylimidazo[2,l ‐b‐ ]thiazole reacts with aryl isothiocyanates to give dipolar 1:1 adducts. The adducts are relatively unstable and, in solution, exist in equilibrium with starting materials. The reaction with aryl and alkyl isocyanates, however, leads to cyclic 2:1 adducts, while sulphonyl and acyl isocyanates give stable dipolar 1:1 adducts. J. Chem. Soc. , 14, 989 (1977)