Retro-ene reactions in heterocyclic synthesis. II. A facile synthetic method for 4-hydroxy-2-pyridones

Schiff's bases 1 derived from ketones and t-butylamine reacted with diphenyl malonate, diphenyl methyl-malonate and diphenyl phenylmalonate to give 4-hydroxy-2-pyridones 4–6 . Schiff's bases b on reaction with trimethyl methanetricarboxylate afforded 4-hydroxy-3-methoxycarbonyl-2-pyridones 12 .