Abstract
3-Amino-2-thiophenecarboxamides (3a-e) were synthesized from 2-(4-oxo-3-phenylthiazolidin- 2-ylidene)malononitrile(1) and employed in the synthesis of a variety of thiophene derivatives. These 3-Amino-2-thiophenecarboxamides (3a-c) which when treated with aromatic aldehydes under relatively mild conditions produced the 3-arylideneamines (6a-d). Treatment of the carboxamide(3d) with triethylorthoformate gave the thiophene-3-ylformimidate (7). Reacting 3-aminothiophene-2-carboxamides (3b,c) with chloroacetyl chloride furnished 5-(2-chloro-N-phenylacetamido)-3-(2-chloroacetamido)-2- carboxamides (8a,b). The 3-amino-2-thiophene carboxamides (3a-e) on reacting with acetic anhydride yielded the thienooxazinone(11). Ethyl 4-cyano-3-[(ethoxymethylene)amino]-5-phenylaminothiophene-2-carboxylate (12) when treated with hydrazine, phenylhydrazine and hydroxylamine yielded some interesting unexpected thiophene derivatives (13), (14) and (15). Key words: 3-arylideneaminothiophene-2-carboxamides, 3,5-(dichloroacetamido)-4-cyano-N-alkylthiophene-2- carboxamide derivatives, ethyl 4-cyano-3-[(ethoxymethylene)amino]-5-phenylaminothiophene-2-carboxylate, 3-amino-3,4-dihydrothieno[3,2-d]pyrimidine-7-carbo- hydrazide, ethyl 2-substituted-5-(pheny laminothio phene)- 3-ylformimidates.