2-Methyl-2H-1,2-benzothia­zin-4(3H)-one 1,1-dioxide

In the title compound, C₉H₉NO₃S, the thia­zine ring adopts a half-chair conformation. The structure is stabilized by an extensive hydrogen-bonded network involving two intra­molecular and three inter­molecular inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.051
• wR factor = 0.124
• Data-to-parameter ratio = 16.2

checkCIF/PLATON results

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Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.06
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.41
           From the CIF: _reflns_number_total               2075
           Count of symmetry unique reflns         1234
           Completeness (_total/calc)            168.15%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       841
           Fraction of Friedel pairs measured     0.682
           Are heavy atom types Z>Si present        yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The term 'oxicam' describes a relatively new enolic acid class of 4-hydroxy-1,2-benzothiazine carboxamides with anti-inflammatory and analgesic properties as tested by Writhing Syndrome (Kwon & Park, 1996). The first member of this class, piroxicam (Lombardino & Wiseman, 1972), was introduced in the United States in 1982 and it gained immediate acceptance and remained among the top 50 prescription drugs for several years. Continuing our investigations in this area (Siddiqui et al., 2006; Siddiqui, Ahmad, Khan, & Siddiqui, 2007; Siddiqui, Ahmad, Khan, Siddiqui & Ahmad, 2007; Siddiqui et al., 2007a,b; Siddiqui, Ahmad, Siddiqui, Khan & Parvez, 2007) we report herein the structure of the title compound, (I).

The heterocyclic thiazine ring in (I) (Fig. 1) adopts a half-chair conformation wherein N1 is displaced by -0.685 (4) Å from the plane defined by the remaining atoms in the ring, with puckering parameters (Cremer & Pople, 1975): Q = 0.526 (1) Å, θ = 50.1 (3)° and ϕ = 54.6 (5)°. The structure is stabilized by two intramolecular hydrogen bonds C8—H8A···O2 and C9—H9B···O3 that result in graph set patterns S(5) and S(6), respectively (Bernstein et al., 1994); details of hydrogen bonding geometry have been provided in a Table. It is interesting to note that O3 is involved in three rather weak intermolecular interactions of the type C—H···O (Fig. 2).

Related literature

For related literature, see: Bernstein et al. (1994); Kwon & Park (1996); Lombardino & Wiseman (1972); Piero et al. (1992); Roberto et al. (1990); Siddiqui, Ahmad, Khan & Siddiqui (2007); Siddiqui, Ahmad, Khan, Siddiqui & Ahmad (2007); Siddiqui et al. (2007a,b); Siddiqui, Ahmad, Siddiqui, Khan & Parvez (2007); Cremer & Pople (1975); Siddiqui et al. (2006).

S2. Experimental

The title compound was synthesized as reported earlier (Roberto et al., 1990; Piero et al., 1992) and was recrystallized from a solution of MeOH at 313 K to obtain colorless crystals.

S3. Refinement

An absolute strucrute was established by the Flack (1983) method using 848 Friedel pairs; Flack parameter, x, was 1.15 (15) for the inverted structure which was therefore, rejected to be the one present in the crystal. H-atoms bonded to C-atoms were included in the refinements at geometrically idealized positions with C—H_aromatic type = 0.95, CH₂ type = 0.99 and CH₃ type = 0.98 Å and U_iso = 1.2 times U_eq of the atoms to which they were bonded. The final difference map was free of any chemically significant features.

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: HKL DENZO (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. The molecular structure with displacement ellipsoids plotted at 50% probability level; intramolecular interactions have been indicated by broken lines.
	Fig. 2. Part of the crystal structure, showing intermolecular interactions of the type C—H···O; intramolecular interactions have been ignored for clarity.

2-Methyl-2H-1,2-benzothiazin-4(3H)-one 1,1-dioxide

Crystal data

C9H9NO3S	F(000) = 440
Mr = 211.23	Dx = 1.527 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2075 reflections
a = 6.778 (5) Å	θ = 2.6–27.4°
b = 8.634 (6) Å	µ = 0.33 mm^−1
c = 15.704 (10) Å	T = 173 K
V = 919.0 (11) Å^3	Prism, colorless
Z = 4	0.12 × 0.10 × 0.08 mm

Data collection

Nonius KappaCCD diffractometer	2075 independent reflections
Radiation source: fine-focus sealed tube	1692 reflections with I > 2 σ(I)
Graphite monochromator	Rint = 0.045
ω and ϕ scans	θmax = 27.4°, θmin = 2.6°
Absorption correction: multi-scan (SORTAV; Blessing, 1997)	h = −8→8
Tmin = 0.962, Tmax = 0.974	k = −11→11
6478 measured reflections	l = −20→20

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.051	H-atom parameters constrained
wR(F^2) = 0.125	w = 1/[σ^2(Fo^2) + (0.045P)^2 + 0.93P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
2075 reflections	Δρmax = 0.70 e Å^−3
128 parameters	Δρmin = −0.34 e Å^−3
0 restraints	Absolute structure: Flack (1983), 848 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.14 (15)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
S1	0.38859 (14)	0.53500 (10)	0.80195 (6)	0.0257 (2)
O1	0.3254 (5)	0.2461 (3)	1.02285 (17)	0.0434 (8)
O2	0.5943 (4)	0.5091 (3)	0.78864 (16)	0.0334 (6)
O3	0.2839 (4)	0.6302 (3)	0.74272 (17)	0.0349 (7)
N1	0.2779 (5)	0.3677 (3)	0.8062 (2)	0.0316 (7)
C1	0.3568 (5)	0.6086 (4)	0.9056 (2)	0.0242 (8)
C2	0.3501 (6)	0.7667 (4)	0.9181 (2)	0.0303 (9)
H2	0.3551	0.8351	0.8708	0.036*
C3	0.3359 (6)	0.8258 (5)	1.0006 (3)	0.0356 (10)
H3	0.3313	0.9345	1.0097	0.043*
C4	0.3285 (6)	0.7255 (5)	1.0688 (3)	0.0369 (10)
H4	0.3226	0.7658	1.1250	0.044*
C5	0.3296 (5)	0.5657 (4)	1.0563 (2)	0.0306 (9)
H5	0.3203	0.4979	1.1038	0.037*
C6	0.3441 (5)	0.5051 (4)	0.9746 (2)	0.0247 (8)
C7	0.3406 (6)	0.3334 (4)	0.9631 (2)	0.0287 (8)
C8	0.3629 (7)	0.2676 (4)	0.8739 (2)	0.0344 (9)
H8A	0.5049	0.2517	0.8620	0.041*
H8B	0.2977	0.1651	0.8717	0.041*
C9	0.0596 (6)	0.3734 (6)	0.8058 (3)	0.0479 (11)
H9A	0.0069	0.2681	0.8008	0.057*
H9B	0.0145	0.4357	0.7574	0.057*
H9C	0.0127	0.4202	0.8589	0.057*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0278 (4)	0.0258 (4)	0.0235 (4)	−0.0017 (4)	0.0001 (4)	0.0021 (4)
O1	0.064 (2)	0.0348 (15)	0.0317 (15)	0.0023 (14)	0.0011 (14)	0.0103 (13)
O2	0.0234 (13)	0.0411 (15)	0.0358 (14)	−0.0007 (12)	0.0056 (12)	−0.0005 (11)
O3	0.0352 (16)	0.0381 (15)	0.0313 (14)	0.0037 (12)	−0.0035 (12)	0.0094 (12)
N1	0.0404 (19)	0.0290 (15)	0.0254 (16)	−0.0083 (13)	0.0017 (16)	−0.0002 (15)
C1	0.0183 (19)	0.0256 (17)	0.0288 (18)	−0.0021 (15)	0.0017 (15)	−0.0007 (14)
C2	0.025 (2)	0.029 (2)	0.037 (2)	−0.0005 (16)	−0.0019 (17)	−0.0006 (16)
C3	0.024 (2)	0.034 (2)	0.049 (3)	0.0015 (16)	−0.0018 (18)	−0.0111 (19)
C4	0.027 (2)	0.047 (3)	0.036 (2)	0.0051 (18)	−0.0013 (17)	−0.0170 (19)
C5	0.028 (2)	0.040 (2)	0.0242 (18)	0.0044 (16)	0.0009 (15)	−0.0044 (15)
C6	0.0243 (19)	0.0281 (19)	0.0218 (16)	0.0013 (13)	−0.0004 (15)	−0.0021 (13)
C7	0.033 (2)	0.0288 (19)	0.0246 (18)	0.0029 (16)	0.0000 (16)	0.0040 (15)
C8	0.055 (3)	0.0204 (17)	0.0274 (18)	0.0010 (19)	0.0067 (19)	0.0033 (14)
C9	0.040 (3)	0.067 (3)	0.037 (2)	−0.027 (2)	−0.003 (2)	0.005 (2)

Geometric parameters (Å, º)

S1—O2	1.428 (3)	C3—H3	0.9500
S1—O3	1.430 (3)	C4—C5	1.393 (6)
S1—N1	1.629 (3)	C4—H4	0.9500
S1—C1	1.760 (4)	C5—C6	1.390 (5)
O1—C7	1.207 (4)	C5—H5	0.9500
N1—C9	1.481 (5)	C6—C7	1.494 (5)
N1—C8	1.487 (5)	C7—C8	1.519 (5)
C1—C2	1.380 (5)	C8—H8A	0.9900
C1—C6	1.407 (5)	C8—H8B	0.9900
C2—C3	1.395 (5)	C9—H9A	0.9800
C2—H2	0.9500	C9—H9B	0.9800
C3—C4	1.379 (6)	C9—H9C	0.9800
O2—S1—O3	118.66 (16)	C6—C5—C4	120.2 (4)
O2—S1—N1	108.48 (17)	C6—C5—H5	119.9
O3—S1—N1	107.92 (18)	C4—C5—H5	119.9
O2—S1—C1	108.16 (16)	C5—C6—C1	118.5 (3)
O3—S1—C1	109.45 (17)	C5—C6—C7	118.9 (3)
N1—S1—C1	103.05 (16)	C1—C6—C7	122.6 (3)
C9—N1—C8	114.2 (3)	O1—C7—C6	121.8 (3)
C9—N1—S1	115.5 (3)	O1—C7—C8	119.4 (3)
C8—N1—S1	111.5 (3)	C6—C7—C8	118.7 (3)
C2—C1—C6	121.1 (3)	N1—C8—C7	113.8 (3)
C2—C1—S1	119.6 (3)	N1—C8—H8A	108.8
C6—C1—S1	119.3 (3)	C7—C8—H8A	108.8
C1—C2—C3	119.8 (4)	N1—C8—H8B	108.8
C1—C2—H2	120.1	C7—C8—H8B	108.8
C3—C2—H2	120.1	H8A—C8—H8B	107.7
C4—C3—C2	119.6 (4)	N1—C9—H9A	109.5
C4—C3—H3	120.2	N1—C9—H9B	109.5
C2—C3—H3	120.2	H9A—C9—H9B	109.5
C3—C4—C5	120.9 (4)	N1—C9—H9C	109.5
C3—C4—H4	119.6	H9A—C9—H9C	109.5
C5—C4—H4	119.6	H9B—C9—H9C	109.5
O2—S1—N1—C9	−170.5 (3)	C3—C4—C5—C6	2.0 (6)
O3—S1—N1—C9	−40.7 (3)	C4—C5—C6—C1	−0.3 (5)
C1—S1—N1—C9	75.0 (3)	C4—C5—C6—C7	−178.7 (3)
O2—S1—N1—C8	57.0 (3)	C2—C1—C6—C5	−1.6 (5)
O3—S1—N1—C8	−173.3 (2)	S1—C1—C6—C5	176.6 (3)
C1—S1—N1—C8	−57.5 (3)	C2—C1—C6—C7	176.8 (3)
O2—S1—C1—C2	93.8 (3)	S1—C1—C6—C7	−5.0 (5)
O3—S1—C1—C2	−36.9 (3)	C5—C6—C7—O1	0.0 (6)
N1—S1—C1—C2	−151.5 (3)	C1—C6—C7—O1	−178.3 (4)
O2—S1—C1—C6	−84.5 (3)	C5—C6—C7—C8	−178.2 (3)
O3—S1—C1—C6	144.9 (3)	C1—C6—C7—C8	3.4 (6)
N1—S1—C1—C6	30.3 (3)	C9—N1—C8—C7	−70.9 (5)
C6—C1—C2—C3	1.7 (6)	S1—N1—C8—C7	62.3 (4)
S1—C1—C2—C3	−176.5 (3)	O1—C7—C8—N1	149.6 (4)
C1—C2—C3—C4	−0.1 (6)	C6—C7—C8—N1	−32.2 (5)
C2—C3—C4—C5	−1.8 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···O3^i	0.95	2.55	3.467 (5)	164
C8—H8A···O3^ii	0.99	2.42	3.240 (5)	140
C9—H9A···O3^iii	0.98	2.40	3.226 (5)	141
C8—H8A···O2	0.99	2.58	2.933 (5)	101
C9—H9B···O3	0.98	2.49	2.865 (5)	102

Symmetry codes: (i) −x+1/2, −y+1, z+1/2; (ii) −x+1, y−1/2, −z+3/2; (iii) −x, y−1/2, −z+3/2.