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

The asymmetric unit of the title compound, C10H9NO5S, contains two independent molecules. The heterocyclic thiazine rings in both molecules adopt half-chair conformations, with the S atoms in each molecule displaced by 0.455 (3) and 0.539 (3) angstrom and the N atoms displaced in the opposite direction by 0.214 (3) and 0.203 (3) angstrom, from the planes defined by the remaining ring atoms. The crystal structure is stabilized by O-H center dot center dot center dot O, N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds involving both inter-and intramolecular interactions.