Synthesis of 3‐amino‐2‐carbamoylthiophene and its reaction with cycloalkanones to form imines

3‐Amino‐2‐carbamoylthiophene (2) was obtained in 75% yield by reaction of methyl 3‐aminothiophene‐2‐carboxylate with saturated aqueous ammonia containing ammonium chloride catalyst at room temperature over a period of 2,3 months, Treatment of 2 with cyclopentanone, cyclohexanone, and cycloheptanone in ethanol at p H 3.4 gave facile formation of 2‐carbamoyl‐3‐cycloalkylidenaminothiophenes in yields of 73%, 86%, and 60%, respectively. Infrared and 1 H nmr spectra of these imines indicate that they occur in intramolecularly hydrogenbonded form, i.e. with chelate rings. Comparison is made with reported syntheses and reactions of 2 and its isosteric 2‐aminobenzamide.