Pharmacologically active 4-oxo-4H-chromen-2-carboxylic acids (2-carboxychromones). Part I. The synthesis of 4-oxo-4H-chromen-2-carboxylic acids containing a fused thiazole ring

Abstract

The synthesis of five 2-carboxychromones containing a fused 2-methylthiazole ring is described. All were obtained from appropriately substituted acetylhydroxybenzothiazoles which were synthesised by several routes but mainly by acetylation of methoxybenzothiazoles under various conditions. A note on the mass spectral fragmentation of the 2-methylthiazolochromone acids is included.