Synthesis and Antibacterial Evaluation of Model Fluoroquinolone- Benzylidene Barbiturate Hybrids

The interaction of 1,3-dimethylbarbituric acid (2) with ethyl 7-chloro-1-cyclopropyl-6-fluoro-8-nitro-4- oxoquinoline-3-carboxylate (1) in basic medium yielded the respective 7-[5-(1,3-dimethylbarbitutic)]-quinoline hybrid (3). Substituted 5-bis(thioethyl)methylene barbituric acids (5a,b) underwent cyclocondensation with 7,8-diamino-6- fluoroquinoline-3-carboxylate (4) to produce the respective fluoroquinolone-benzylidene-barbiturate hybrids (6a,b) incorporating fused-imidazoline moiety. Saponification of the dimethylated ester (6b) gave the respective acid (7). The new compounds (3,5-7) show low to moderate antibacterial activity against Staphylococcus aureus and E. coli.