Methyl 2-ethyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide

In the title compound, C12H13NO5S, the thiazine ring adopts a half chair conformation and an intramolecular O—H...O hydrogen bond generates an S(6) ring. In the crystal, the molecules are linked by C—H...O interactions, leading to zigzag chains along the b axis