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

Molecules. 2008 Jan 30;13(1):195-203. doi: 10.3390/molecules13010195.

Abstract

Some novel Schiff bases have been prepared by reacting 6-azido-5-formyl-2-pyridone 1 with a series of aromatic amines 2a-f. 5-Arylaminomethylene-6-(E)-aryl-iminopyridones 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 degrees 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 1H- and 13C-NMR spectroscopy.

MeSH terms

  • Amines / chemistry*
  • Isomerism
  • Pyridones / chemical synthesis
  • Pyridones / chemistry*
  • Schiff Bases / chemical synthesis*
  • Schiff Bases / chemistry*
  • Schiff Bases / isolation & purification

Substances

  • 6-azido-5-formyl-2-pyridone
  • Amines
  • Pyridones
  • Schiff Bases