Pharmacologically active 4-oxo-4H-chromen-2-carboxylic acids. Part II. The synthesis of 4-oxo-4H-chromen-2-carboxylic acids containing a fused imidazole or oxazole ring

Abstract

The synthesis of various 2-carboxychromones containing a fused imidazole or oxazole ring is described. The imidazolochromones were prepared either from appropriately substituted vic-acetylhydroxybenzimidazoles or from vic-diaminochromones; the oxazolochromones were obtained either from vic-aminohydroxychromones, or by decomposition of azidochromones in the presence of polyphosphoric acid and a carboxylic acid.