(2-Chlorophenyl)(4-hydroxy-1,1-dioxo-2H-1,2-benzothiazin-3-yl)methanone

In the title molecule, C15H10ClNO4S, the heterocyclic thiazine ring adopts a half-chair conformation, with the S and N atoms displaced by 0.527 (7) and 0.216 (7) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The molecular structure is consolidated by an intramolecular O—H⋯O interaction and the crystal packing is stabilized by N—H⋯O and C—H⋯O hydrogen bonds.

In the title molecule, C 15 H 10 ClNO 4 S, the heterocyclic thiazine ring adopts a half-chair conformation, with the S and N atoms displaced by 0.527 (7) and 0.216 (7) Å , respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The molecular structure is consolidated by an intramolecular O-HÁ Á ÁO interaction and the crystal packing is stabilized by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds.

Parvez Comment
The nucleus 1,2-benzothiazine 1,1-dioxide represents a class of pharmaceutically important heterocyclic compounds that have received considerable attention because of their dynamic structural features and a wide range of biological activities.
They are known to be anti-allergy (Ikeda et al., 1992), anti-inflammatory (Lombardino et al., 1973), analgesic (Gupta et al., 2002), anti-bacterial (Zia-ur-Rehman et al., 2006 etc. In continuation of our research on the synthesis of biologically active benzothiazine derivatives (Siddiqui et al., 2007;Ahmad et al., 2010) we report herein the synthesis and crystal structure of the title compound.
The bond distances and angles in the title compound ( Fig. 1) agree very well with the corresponding bond distances and angles reported for its bromo analogue with which it is isomorphic (Sattar et al., 2012). The heterocyclic thiazine ring adopts a half chair conformation with atoms N1 and S1 displaced by 0.216 (7) and 0.527 (7) Å, respectively, on the opposite sides from the mean plane formed by the remaining ring atoms. The molecular structure is stabilized by intramolecular interactions O4-H4O···O3 and the crystal packing is consolidated by N1-H1N···O4 and C13-H13···O2 intermolecular hydrogen bonds ( Figure 2 and Table 1).

Refinement
The H atoms bonded to C and O atoms were positioned geometrically and refined using a riding model, with O-H and C-H = 0.84 and 0.95 Å, respectively. The amino H-atom was allowed to refine freely. The U iso (H) were allowed at 1.2U eq (parent atom).  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.