1-(4-Hydr­oxy-2-methyl-1,1-dioxo-2H-1,2-benzothia­zin-3-yl)ethanone

Matloob Ahmad; Hamid Latif Siddiqui; Muhammad Zia-ur-Rehman; Muhammad Irfan Ashiq; Graham John Tizzard

doi:10.1107/S1600536808007721

. 2008 Apr 2;64(Pt 5):o788. doi: 10.1107/S1600536808007721

1-(4-Hydroxy-2-methyl-1,1-dioxo-2H-1,2-benzothiazin-3-yl)ethanone

Matloob Ahmad ^a,^*, Hamid Latif Siddiqui ^a, Muhammad Zia-ur-Rehman ^b, Muhammad Irfan Ashiq ^c, Graham John Tizzard ^c

PMCID: PMC2961329 PMID: 21202281

Abstract

In the title compound, C₁₁H₁₁NO₄S, the thiazine ring adopts a distorted half-chair conformation. The enolic H atom is involved in an intramolecular O—H⋯O hydrogen bond, forming a six-membered ring. Molecules are linked through weak intermolecular C—H⋯O hydrogen bonds, resulting in chains lying along the b axis.

Related literature

For related literature, see: Bihovsky et al. (2004 ▶); Fabiola et al. (1998 ▶); Golič & Leban (1987 ▶); Zia-ur-Rehman et al. (2005 ▶, 2006 ▶, 2007 ▶); Turck et al. (1996 ▶).

Experimental

Crystal data

C₁₁H₁₁NO₄S
M _r = 253.27
Triclinic,
a = 6.8523 (1) Å
b = 8.3222 (2) Å
c = 10.4880 (2) Å
α = 72.1321 (11)°
β = 77.9619 (12)°
γ = 80.0360 (12)°
V = 552.89 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.29 mm⁻¹
T = 120 (2) K
0.40 × 0.20 × 0.14 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2007 ▶) T _min = 0.891, T _max = 0.960
12691 measured reflections
2529 independent reflections
2248 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.092
S = 1.11
2529 reflections
157 parameters
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.53 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: DENZO (Otwinowski & Minor, 1997 ▶); data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: CAMERON (Pearce & Watkin, 1993 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808007721/pv2072sup1.cif

e-64-0o788-sup1.cif^{(16KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808007721/pv2072Isup2.hkl

e-64-0o788-Isup2.hkl^{(121.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3A⋯O4	0.84	1.78	2.525 (2)	146
C4—H4⋯O2ⁱ	0.95	2.36	3.193 (2)	146

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Symmetry code: (i) Inline graphic .

Acknowledgments

We gratefully acknowledge the Higher Education Commission of Pakistan and the University of the Punjab, Lahore, for financial support.

supplementary crystallographic information

Comment

In order to discover new useful therapeutic agents, many new compounds are continuously being synthesized. Benzothiazine dioxides and their derivatives are reported to possess numerous types of biological activities. Owing to their applications as non-steroidal anti-inflammatory compounds (Turck et al., 1996), considerable attention has been given to 1,2-benzothiazine 1,1-dioxides and their precursor intermediates (Golič & Leban, 1987). Various 1,2-benzothiazines derivatives are also known as potent calpain I inhibitors (Bihovsky et al., 2004), while benzothiaine-3-yl-quinazolin-4-ones showed marked activity against Bacillus subtilis (Zia-ur-Rehman et al., 2006). As part of a research program synthesizing various bioactive benzothiazines (Zia-ur-Rehman et al., 2005, 2006), we herein report the crystal structure of the title compound, (I).

In the molecule of the title compound (Fig. 1), the thiazine ring exhibits a distorted half-chair conformation with S1/C1/C6/C7 atoms lying in a plane and N1 showing significant departure from the plane due to its pyramidal geometry projecting the methyl group approximately perpendicular to the ring; the deviations of N1 and C8 from the least square plane being -0.895 (2) and -0.413 (3) Å, respectively. Like other 1,2-benzothiazine 1,1-dioxide derivatives (Fabiola et al., 1998; Zia-ur-Rehman et al., 2007), the enolic hydrogen on O3 is involved in intramolecular hydrogen bonding (Table 1). Also, C7—C8 bond length [1.378 Å] (very close to normal C?C bond; 1.36 Å) indicates a partial double-bond character indicating the dominance of enolic form in the molecule. The C1—S1 bond distance [1.7580 (14) Å] is as expected for typical C(sp²)—S bond (1.751 Å).

Each molecule is linked to its adjacent one through a hydrogen bond [C4—H4···O2] resulting in a chain of molecules lying along the b axis (Table 1 and Fig. 2). Each molecule in the chain is linked with its neighbour through weak slipped π-π interactions at inversion centres; the closest C–C contacts are between C3–C3ⁱ separated by 3.316 Å.

Experimental

A mixture of 1-(4-hydroxy-1,1-dioxido-2H-1,2-benzothiazin-3-yl) ethanone (239 mg, 1.0 mmol) dissolved in acetone (10 ml), aqueous NaOH (3 ml, 5%) and dimethyl sulfate (0.5 ml) was stirred for half an hour followed by careful addition of dilute HCl (5%) to maintain the pH to Congo Red. Precipitates of (I) thus obtained were filtered, washed with water and dried. Colourless crystals were grown by slow evaporation of a solution of (I) in methanol at room temperature.