Hypervalent iodine mediated synthesis of 1,2,4-triazolo [4,3-a] [1,8]naphthyridines

2-Aminonicotinaldehyde 1 on condensation with p-chlorophenylacetonitrile 2 affords 2-amino-3-(p-chlorophenyl)-1,8-naphthyridine 3, which is converted into 2-hydrazino-3-(p-chlorophenyl)-1,8-naphthyridine 4 by the reaction with hydrazine hydrate and conc. HCL The hydrazino compound 4 undergo condensation with aromatic aldehydes to give the corresponding 3-(p-chlorophenyl)-1,8-naphthyridin-2-ylhydrazones 5, which on oxidation with iodobenzene diacetate (IBD) in dichloromethane at room temperature furnishes 1-aryl-4-(p-chlorophenyl)-1,2,4-triazolo[4,3-a][1,8]naphthyridines 6. Structural assignments of the products are based on their elemental analyses and spectral (IR, H-1 NMR and MS) data. Compounds 6 synthesized have been screened for their antibacterial activity.