C-acylation of heterocyclic keto-enols Communication 8. 3-acyl-4-hydroxy-6-methyl-2(lH)-pyridones and their 1-methyl derivatives

Abstract

1. The acetylation of 4-hydroxy-6-methyl-2(1H)-pyridone and its 1-methyl derivative was studied. By the action of acetic acid in presence of phosphoryl chloride, from the first substance the C-acetylation product -3-acetyl-4-hydroxy-6-methyl-2(1H)-pyridone- was obtained, and from the second substance the O-acetylation product -4-acetoxy-l,6-dimethyl-2(1H)-pyridone- was obtained. In presence of polyphosphoric acid the C-acylation product was obtained in both cases. 2. The structure of the C-acetylation products was proved by independent syntheses and a comparison of the IR spectra. 3. The general character of the C-acylation reaction of 4-hydroxy-6-methyl-2(lH)-pyridone with aliphatic acids in presence of polyphosphoric acid was confirmed by the preparation of a number of its 3-acyl derivatives, the structure of which was proved on the basis of the UV and IR spectra.