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Synthesis of 3‐amino‐2‐carbamoylthiophene and its reaction with cycloalkanones to form imines
Author(s) -
Klemm L. H.,
Wang Jun,
Hawkins Lucas
Publication year - 1995
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570320361
Subject(s) - chemistry , cyclopentanone , cyclohexanone , yield (engineering) , ethanol , ammonia , catalysis , medicinal chemistry , ammonium chloride , ammonium , organic chemistry , aqueous solution , materials science , metallurgy
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.