First Synthesis and Isolation of the E- and Z-Isomers of Some New Schiff Bases. Reactions of 6-Azido-5-Formyl-2-Pyridone with Aromatic Amines

Abstract

Abstract: Some novel Schiff bases have been prepared by reacting 6-azido-5-formyl-2pyridone 1 with a series of aromatic amines 2a-f. 5-Arylaminomethylene-6-(E)-aryliminopyridones 3a-e were obtained by reaction of 1 with 2a-e at room temperature, whereas with 2f, the 6-azido-5-naphthalen-2-yl-iminomethylpyridone derivative 4 was formed. On the other hand, heating 1 with 2a-d at 140-150°C yielded two sets of isomeric products, (E)-3a-d and (Z)-5a-d. Refluxing compounds (Z)-3a,c with hydroxyl-amine in methanol gave the corresponding hydroxyliminopyridones 8a,c. Heating of (E)-3a-d with excess POCl3 at reflux did not give the expected tricyclic compound 9, but rather the isomeric products (Z)-5a-d were obtained. The structures of all these products have been characterized using IR and 1 H- and 13 C-NMR spectroscopy