Synthesis and antimicrobial activity of 1,8-naphthyridinyl-4-thiazolidinones/1,3-thiazin-4-ones/2-azetidinones

Condensation of 2-aminonicotinaldehyde 1 with p-acetamido-acetophenone 2 af fords 2-(p-acetamidophenyl)-1,8-naphthyridine 3, which on acidic hydrolysis yields 2-(p-aminophenyl)-1,8-naphthyridine. 4. The amino compound 4 underg o condensation with aromatic aldehydes to give corresponding 2-(p-arylidene aminophenyl)-1,8-naphthyridines 5. Cyclocondensation of 5 with mercaptoacet ic acid and beta-mercaptopropionic acid separately in DMF in the presence o f anhyd. ZnCl2 results in the formation of 1,8-naphthyridinyl-4-thiazolidin ones 6 and 1,8-naphthyridinyl-1,3-thiazin-4-ones 7, respectively. On the ot her hand, the arylidene derivatives 5 on cycloaddition with chloroacetyl ch loride in the presence of triethylamine in dry 1,4-dioxane furnishes the de sired 1,8-naphthyridinyl-2-azetidinones 8. The structures of the compounds 3-8 have been established on the basis of their elemental analyses and spec tral (IR, H-1 NMR and mass) data. Some of the compounds have been screened for their antibacterial and antifungal activities.