4-Hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid ethylester 1,1-dioxide

It acts as the core benzothiazine precursor that undergoes aminolysis with 2-amino-5-methylthiazole, typically at 140–189°C in solvents like DMSO or xylene to form the anti-inflammatory drug. 4-Hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid ethyl ester 1,1-dioxide is a key intermediate (often identified as Meloxicam Impurity A) used to synthesize Meloxicam.