2-(3,4-Dimethyl-5,5-dioxo-2H,4H-pyrazolo-[4,3-c][1,2]benzothia-zin-2-yl)acetic acid.

In the title mol-ecule, C(13)H(13)N(3)O(4)S, the heterocyclic thia-zine ring adopts a half-chair conformation in which the S and an adjacent C atom are displaced by 0.919 (3) and 0.300 (4) Å, respectively, on the same side of the mean plane formed by the remaining ring atoms. The mean planes of the benzene and pyrazole rings are inclined at a dihedral angle of 18.32 (12)° with respect to each other. The acetate group is oriented at 80.75 (8)° with respect to the pyrazole ring. The crystal structure is stabilized by O-H⋯N and C-H⋯O hydrogen bonds, resulting in fused eight- and seven-membered rings with R(2) (2)(8) and R(2) (2)(7) graph-set motifs, respectively.