Utilization of 2-Ylidene-4-Thiazolidinones in the Synthesis of Heterocyclic Compounds Part III: Synthesis and In-Vitro Antibacterial Activity Evaluation of Thienopyrimidinone Derivatives

3-Amino-2-thiophenecarboxamides (3a, d-g) were synthesized from 2-(4-oxo-3-phenyl- thiazolidin-2-ylidene)malononitrile (2) and employed in the synthesis of a variety of thiophene and thienopyrimidinone derivatives. 3 -Amino-2-thiophenecarboxamides (3a, d, e) on refluxing in acetic acid gave the tetrahydrothienopyrimidinones (6a-m). On the other hand, the reaction of the 3-amino-2-thiophenecarboxamides (3a, d, e) with triethylorthoformate or with formic acid produced the dihydrothienopyrimidinones (7a-c). The synthesized heterocyclic compounds were screened for antibacterial activities using narrow spectrum against gram-positive and gram-negative bacteria.