Methyl 2-(but-3-enyl)-4-hydroxy-1,1-dioxo-2H-1λ6,2-benzothiazine-3-carboxylate

In the title compound, C14H15NO5S, the thiazine ring adopts a sofa conformation and an intramolecular O—H⋯O hydrogen bond forms an S(6) ring. In the crystal, molecules are linked viaC—H⋯O interactions.