Methyl 5-chloro-4-hydroxy-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylate: structure and Hirshfeld surface analysis

The title compound, C10H8ClNO5S, which has potential analgesic activity, crystallizes in space group P21/n. The benzothiazine ring system adopts an intermediate form between sofa and twist-boat conformations. The coplanarity of the ester substituent to the bicyclic fragment is stabilized by an O—H...O intramolecular hydrogen bond. In the crystal, hydrogen bonds of type N—H...O(SO2) link the molecules into zigzag chains extending along the b-axis direction. Neighbouring chains are linked by both O—H...Cl and C—H...Cl interactions. A Hirshfeld surface analysis was used to compare different types of intermolecular interactions, giving contributions of O...H/H...O = 42.0%, C...H/H...C = 17.3%, Cl...H/H...Cl = 14.2%, H...H = 11.1%.