Studies on the Syntheses of 2 (1H)-Pyridone Derivatives. IV. Synthesis of Condensed Heterocyclic 2 (1H)-Pyridones

Abstract

Condensation of 4-cyano-3-butenoates (IV) with 1, 2-diamine or 1, 2-aminothiol was carried out. Imidazopyridones were obtained by the reaction of IV with aliphatic 1, 2-diamine. The reaction of IV with o-phenylenediamine resulted in the formation of imino-pyridobenzimidazole (VII), which was converted to the corresponding pyridone derivative (IX) on hydrolysis. The predominant tautomeric forms of VII and IX are discussed on the basis of nuclear magnetic resonance and ultraviolet spectra. In the reaction of IV with 2-aminoethanethiol or o-aminothiophenol, the thiazoline ring was formed by condensation between the cyano group of IV and the amino and thiol groups of the 1, 2-aminothiol, and the resulting thiazoline compound was further converted into thiazolopyridone or oxo-pyridobenzothiazole, respectively, by cyclization with an acid catalyst. Some of these pyridone derivatives showed strong anti-inflammatory activity.