Synthesis of 4-thiazolidinone and 2-azetidinone derivatives of 2-trifluoromethyl-1,8-naphthyridine as antibacterial agents

Ethyl 2-trifluoromethyl-1,8-naphthyridine-3-carboxylate 3 has been synthesi zed by the condensation of 2-aminonicotinaldehyde 1 with ethyl trifluoroace toacetate 2 and subjected to hydrazinolysis with refluxing hydrazine hydrat e to give 2-trifluoromethyl-1,8-naphthyridine-3-carboxylic acid hydrazide 4 . The acid hydrazide 4 reacts with aromatic aldehydes to yield the correspo nding 2-trifluoromethyl-1,8-naphthyridine-3-carboxylic acid arylidenehydraz ides 5. Cyclocondensation of 5 with mercaptoacetic acid in DMF in the prese nce of anhyd. ZnCl2 affords 2-aryl-3-(2-trifluoromethyl-1,8-naphthyridine-3 -carbonylamino)-4-thiazolidinones 6. On the other hand, cycloaddition of ch loroacetyl chloride to 5 in dioxane in the presence of Et3N gives 4-aryl-3- chloro-1-(2-trifluoromethyl-1,8-naphthyridine-3-carbonylamino)-2-azetidinon es 7. These compounds have been characterized on the basis of elemental ana lyses, IR, H-1 NMR and MS. All the products have been evaluated for antibac terial activity.