Mol­ecular and crystal structure of methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzo­thia­zine-3-carboxyl­ate

Shishkina, S.; Ukrainets, I.; Hamza, G.; Grinevich, L.

doi:10.1107/S2056989018011362

research communications

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ISSN: 2056-9890

Volume 74| Part 9| September 2018| Pages 1299-1301

https://doi.org/10.1107/S2056989018011362

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Molecular and crystal structure of methyl 4-methyl-2,2-dioxo-1H-2λ⁶,1-benzothiazine-3-carboxylate

Svitlana Shishkina,^a,^b ^* Igor Ukrainets,^c Ganna Hamza ^c and Lina Grinevich ^c

^aSSI "Institute for Single Crystals" National Academy of Sciences of Ukraine, 60, Nauky ave., Kharkiv 61001, Ukraine, ^bV.N. Karazin Kharkiv National University, 4 Svobody, Kharkiv 61077, Ukraine, and ^cNational University of Pharmacy, 4 Valentinovska Str., Kharkiv 61168, Ukraine
^*Correspondence e-mail: sveta@xray.isc.kharkov.com

Edited by P. Bombicz, Hungarian Academy of Sciences, Hungary (Received 24 July 2018; accepted 9 August 2018; online 21 August 2018)

The title compound, C₁₁H₁₁NO₄S, possesses weak analgesic properties and is a source compound for the synthesis of highly active analgesic and anti-inflammatory compounds. The benzothiazine ring adopts a conformation intermediate between twist-boat and sofa. The ester substituent is turned towards the endocyclic double bond because of steric repulsion. In the crystal, the molecules form columns along the [001] direction, bound by N—H⋯O hydrogen bonds and stacking interactions.

Keywords: 1,2-benzothiazine derivatives; molecular and crystal structure; hydrogen bonding; π-stacking interaction.

CCDC reference: 1861156

1. Chemical context

Methyl 4-methyl-2,2-dioxo-1H-2λ⁶,1-benzothiazine-3-carboxylate (I) displays moderate analgesic properties (Azotla-Cruz et al., 2017 ) but has been used for the synthesis of highly active analgesic and anti-inflammatory compounds (Ukrainets et al., 2018 ). Earlier it was shown (Ukrainets et al., 2016a ,b ) that the biological properties of 2,1-benzothiazine derivatives depend to a considerable degree on their molecular and crystal structures. Thus knowledge of both the molecular and crystal structures of I is very important.

2. Structural commentary

The molecular structure of the title compound is shown in Fig. 1. The dihydrothiazine heterocycle adopts a twist-boat conformation with puckering parameters (Zefirov et al., 1990 ) S = 0.57, Θ = 53.3°, Ψ = 25.2°. The S1 and C8 atoms deviate from the mean plane of the remaining ring atoms by 0.7941 (6) and 0.260 (2) Å, respectively. Some steric repulsion between the methyl substituent at the C7 atom and the ester group [the short intramolecular contact C11⋯O1 is 2.986 (5) Å compared to the van der Waals radii sum of 3.00 Å (Zefirov, 1997 )] is compensated for by the formation of the intramolecular C11—H11C⋯O1 hydrogen bond (Table 1). As a result, the ester substituent is turned relative to the C7=C8 endocyclic double bond [C7=C8—C9—O1 torsion angle is −35.2 (5)°] and the C7=C8 [1.359 (4) Å] and C8—C9 [1.504 (3) Å] bonds are elongated compared to the standard values (Bürgi & Dunitz, 1994 ) of 1.326 and 1.455 Å, respectively. The methyl group of the ester substituent is in an anti-periplanar conformation relative to the C8—C9 bond [C8—C9—O2—C10 = 174.5 (2)°].

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11C⋯O1	0.96	2.24	2.986 (5)	133
N1—H1N⋯O4ⁱ	0.81 (4)	2.09 (4)	2.891 (3)	170 (4)
C4—H4⋯O3ⁱⁱ	0.93	2.55	3.427 (3)	158
Symmetry codes: (i) $[x, -y, z-{\script{1\over 2}}]$ ; (ii) $[x-1, -y, z+{\script{1\over 2}}]$ .

Figure 1
The molecular structure of I with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

3. Supramolecular features

In the crystal, molecules of I form columns along the [001] direction (Fig. 2). Neighboring molecules within the column are linked by the N1—H1N⋯O4ⁱ hydrogen bonds (Table 1) and π-stacking interactions with centroid–centroid diatances of 3.870 (2) Å. The columns are connected by weak C4—H4⋯O3ⁱⁱ hydrogen bonds (Table 1).

Figure 2
The packing showing columns of molecules along the c-axis direction.

4. Database survey

An search of the Cambridge Structural Database (Version 5.39, update February 2018; Groom et al., 2016 ) revealed only three similar 1,2-benzothiazine derivatives with a methyl substituent at the C7 atom (VAZQEV and VAZQIZ, Azotla-Cruz et al., 2017; OWUQII, Azotla-Cruz et al., 2016 ). All of these compounds are substituted at the nitrogen atom and have very similar molecular structures. The structure VAZQEV differs from others by the trans-orientation of the carbonyl group of the ester substituent relative to the endocyclic double bond.

4.1. Synthesis and crystallization

Methyl (chlorosulfonyl)acetate (1.90 g, 0.011 mol) was added dropwise with stirring to a solution of ortho-aminoacetophenone (1.35 g, 0.010 mol) and triethylamine (1.54 mL, 0.011 mol) in CH₂Cl₂ (20 mL) and cooled to 268–273 K. After 10 h, water (50 mL) was added to the reaction mixture, which was then acidified to pH 4 with 1 N HCl and mixed thoroughly. The organic layer was separated off, dried over anhydrous CaCl₂, and the solvent distilled (at reduced pressure at the end). The resulting anilide was subjected to heterocyclization without purification. A solution of sodium methylate in anhydrous methanol [from metallic sodium (0.69 g, 0.030 mol) and absolute methanol (15 mL)], the mixture was boiled and then kept for 15 h at room temperature. The reaction mixture was diluted with cold water and acidified with 1 N HCl to pH 4. Finally, the solid ester, I, was separated by filtration, washed with water, and dried in air giving colourless block-shaped crystals, yield: 2.25 g (89%); m.p. 476–578 K (methanol); R_{f =} 0.37. ¹H NMR (400 MHz, DMSO-d₆): δ 11.84 (br s, 1H, NH), 7.79 (d, 1H, J = 7.6 Hz, H-5), 7.49 (t, 1H, J = 7.2 Hz, H-7), 7.22 (t, 1H, J = 7.6 Hz, H-6), 7.12 (d, 1H, J = 8.0 Hz, H-8), 3.84 (s, 3H, OCH₃), 2.46 (s, 3H, 4-CH₃, coincides with the signal of residual protons DMSO-d₆). ¹³C-NMR (100 MHz, DMSO-d₆ + CDCl₃): δ 161.6 (C=O), 147.7, 138.2, 132.2, 127.4, 127.1, 123.0, 121.3, 118.8, 52.9 (OCH₃), 17.5 (4-CH₃). MS (m/z, %): 253 [M]⁺ (4.4), 252 [M − H]+ (1.5), 221 [M − CH₃OH]⁺ (8.4), 195 (80.2), 119 (75.3), 103 (17.0), 93 (100), 92 (59.5), 77 (50.0). Analysis calculated for C₁₁H₁₁NO₄S: C, 52.16; H, 4.38; N, 5.53; S 12.66%. Found: C, 52.07; H, 4.30; N, 5.46; S 12.72%.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. All of the H atoms were located in difference-Fourier maps. The N-bound H atoms were refined isotropically. The C-bound H atoms were included in calculated positions and treated as riding: C—H = 0.96 Å with U_iso(H) =1.5U_eq(C) for the methyl groups and C—H = 0.93 Å with U_iso(H) = 1.2U_eq(C) for all others.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₁H₁₁NO₄S
M_r	253.27
Crystal system, space group	Monoclinic, Pc
Temperature (K)	293
a, b, c (Å)	7.8367 (3), 9.6842 (4), 7.5006 (4)
β (°)	93.468 (4)
V (Å³)	568.19 (4)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.29
Crystal size (mm)	0.21 × 0.18 × 0.15

Data collection
Diffractometer	Agilent Xcalibur Sapphire3
Absorption correction	Multi-scan (CrysAlis RED; Agilent, 2012 )
T_min, T_max	0.809, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	5509, 3068, 2803
R_int	0.026
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.085, 1.04
No. of reflections	3068
No. of parameters	160
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.21
Absolute structure	Flack x determined using 1127 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	0.04 (5)
Computer programs: CrysAlis CCD and CrysAlis RED (Agilent, 2012), SHELXS2014/7 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ) and Mercury (Macrae et al., 2008 ).

Supporting information

CCDC reference: 1861156

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989018011362/zp2032sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018011362/zp2032Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989018011362/zp2032Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis CCD (Agilent, 2012); cell refinement: CrysAlis RED (Agilent, 2012); data reduction: CrysAlis RED (Agilent, 2012); program(s) used to solve structure: SHELXS2014/7 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014/7 (Sheldrick, 2015).

Methyl 4-methyl-2,2-dioxo-1H-2λ⁶,1-benzothiazine-3-carboxylate top

Crystal data top

C₁₁H₁₁NO₄S	F(000) = 264
M_r = 253.27	D_x = 1.480 Mg m⁻³
Monoclinic, Pc	Mo Kα radiation, λ = 0.71073 Å
a = 7.8367 (3) Å	Cell parameters from 2089 reflections
b = 9.6842 (4) Å	θ = 4.2–30.6°
c = 7.5006 (4) Å	µ = 0.29 mm⁻¹
β = 93.468 (4)°	T = 293 K
V = 568.19 (4) Å³	Block, colourless
Z = 2	0.21 × 0.18 × 0.15 mm

Data collection top

Agilent Xcalibur Sapphire3 diffractometer	3068 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2803 reflections with I > 2σ(I)
Detector resolution: 16.1827 pixels mm^-1	R_int = 0.026
ω–scans	θ_max = 30.0°, θ_min = 3.4°
Absorption correction: multi-scan (CrysAlis RED; Agilent, 2012)	h = −10→11
T_min = 0.809, T_max = 1.000	k = −9→13
5509 measured reflections	l = −10→10

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.035	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.085	w = 1/[σ²(F_o²) + (0.0399P)²] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3068 reflections	Δρ_max = 0.19 e Å⁻³
160 parameters	Δρ_min = −0.21 e Å⁻³
2 restraints	Absolute structure: Flack x determined using 1127 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (5)

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
S1	0.82278 (8)	0.16925 (5)	0.52933 (8)	0.03401 (14)
O1	0.6143 (4)	0.5195 (2)	0.4202 (4)	0.0679 (7)
O2	0.8581 (3)	0.4555 (2)	0.5668 (3)	0.0514 (5)
O3	0.9468 (3)	0.2019 (2)	0.4041 (3)	0.0477 (5)
O4	0.8846 (2)	0.15240 (18)	0.7126 (2)	0.0416 (4)
N1	0.7250 (3)	0.0322 (2)	0.4558 (3)	0.0420 (5)
H1N	0.780 (5)	−0.012 (4)	0.388 (5)	0.064 (11)*
C1	0.5686 (3)	−0.0083 (2)	0.5189 (3)	0.0364 (5)
C2	0.5276 (4)	−0.1480 (3)	0.5226 (4)	0.0459 (6)
H2	0.6049	−0.2136	0.4864	0.055*
C3	0.3720 (5)	−0.1882 (3)	0.5802 (4)	0.0558 (8)
H3	0.3433	−0.2814	0.5814	0.067*
C4	0.2584 (4)	−0.0915 (4)	0.6361 (4)	0.0570 (8)
H4	0.1550	−0.1198	0.6786	0.068*
C5	0.2967 (4)	0.0469 (3)	0.6297 (4)	0.0469 (6)
H5	0.2174	0.1112	0.6652	0.056*
C6	0.4538 (3)	0.0927 (3)	0.5705 (3)	0.0374 (5)
C7	0.4909 (3)	0.2408 (3)	0.5508 (3)	0.0384 (5)
C8	0.6512 (3)	0.2858 (3)	0.5222 (3)	0.0365 (5)
C9	0.7020 (4)	0.4337 (3)	0.4961 (4)	0.0431 (6)
C10	0.9327 (5)	0.5898 (3)	0.5392 (5)	0.0634 (9)
H10A	1.0462	0.5924	0.5949	0.095*
H10B	0.8640	0.6595	0.5908	0.095*
H10C	0.9375	0.6066	0.4134	0.095*
C11	0.3470 (5)	0.3403 (3)	0.5685 (6)	0.0599 (10)
H11A	0.3055	0.3331	0.6860	0.090*
H11B	0.2562	0.3192	0.4811	0.090*
H11C	0.3869	0.4326	0.5498	0.090*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0300 (3)	0.0345 (2)	0.0379 (3)	0.0013 (2)	0.0052 (2)	0.0017 (2)
O1	0.0679 (16)	0.0430 (11)	0.0907 (18)	0.0062 (10)	−0.0134 (14)	0.0153 (11)
O2	0.0499 (13)	0.0386 (9)	0.0646 (14)	−0.0088 (9)	−0.0041 (10)	0.0034 (8)
O3	0.0423 (11)	0.0504 (11)	0.0519 (12)	0.0000 (9)	0.0161 (9)	0.0048 (9)
O4	0.0372 (10)	0.0453 (10)	0.0421 (11)	−0.0009 (7)	−0.0014 (8)	0.0061 (7)
N1	0.0383 (12)	0.0385 (11)	0.0505 (13)	−0.0010 (9)	0.0116 (10)	−0.0106 (9)
C1	0.0333 (12)	0.0388 (12)	0.0367 (13)	−0.0032 (10)	0.0000 (10)	−0.0034 (9)
C2	0.0472 (16)	0.0391 (13)	0.0508 (16)	−0.0035 (11)	−0.0007 (13)	0.0006 (11)
C3	0.059 (2)	0.0488 (16)	0.059 (2)	−0.0186 (14)	0.0022 (15)	0.0046 (12)
C4	0.0461 (17)	0.072 (2)	0.0530 (17)	−0.0189 (15)	0.0062 (13)	0.0059 (15)
C5	0.0349 (13)	0.0617 (17)	0.0444 (15)	−0.0021 (12)	0.0040 (12)	−0.0013 (12)
C6	0.0323 (12)	0.0426 (13)	0.0369 (12)	0.0005 (10)	−0.0004 (9)	−0.0029 (9)
C7	0.0328 (12)	0.0405 (13)	0.0416 (13)	0.0036 (10)	−0.0010 (10)	−0.0047 (10)
C8	0.0370 (13)	0.0343 (11)	0.0383 (13)	0.0052 (9)	0.0010 (10)	−0.0012 (9)
C9	0.0474 (15)	0.0347 (12)	0.0469 (16)	0.0045 (11)	−0.0004 (13)	−0.0027 (10)
C10	0.069 (2)	0.0425 (17)	0.078 (2)	−0.0173 (15)	0.0017 (18)	−0.0029 (15)
C11	0.0372 (17)	0.0518 (15)	0.091 (3)	0.0120 (13)	0.0055 (18)	−0.0072 (15)

Geometric parameters (Å, º) top

S1—O3	1.4271 (19)	C1—C6	1.400 (3)
S1—O4	1.4391 (19)	C2—C3	1.375 (5)
S1—N1	1.613 (2)	C3—C4	1.375 (5)
S1—C8	1.754 (3)	C4—C5	1.375 (4)
O1—C9	1.199 (4)	C5—C6	1.406 (4)
O2—C9	1.321 (4)	C6—C7	1.472 (4)
O2—C10	1.446 (4)	C7—C8	1.359 (4)
N1—C1	1.397 (3)	C7—C11	1.496 (4)
C1—C2	1.391 (3)	C8—C9	1.503 (4)

O3—S1—O4	116.79 (13)	C4—C5—C6	121.1 (3)
O3—S1—N1	106.58 (13)	C1—C6—C5	117.2 (2)
O4—S1—N1	111.04 (12)	C1—C6—C7	121.3 (2)
O3—S1—C8	112.85 (12)	C5—C6—C7	121.4 (3)
O4—S1—C8	108.38 (12)	C8—C7—C6	121.2 (2)
N1—S1—C8	99.88 (13)	C8—C7—C11	121.1 (3)
C9—O2—C10	117.3 (2)	C6—C7—C11	117.7 (2)
C1—N1—S1	121.58 (18)	C7—C8—C9	125.5 (2)
C2—C1—N1	119.2 (2)	C7—C8—S1	120.2 (2)
C2—C1—C6	121.4 (2)	C9—C8—S1	114.1 (2)
N1—C1—C6	119.3 (2)	O1—C9—O2	124.7 (3)
C3—C2—C1	119.5 (3)	O1—C9—C8	125.0 (3)
C2—C3—C4	120.4 (3)	O2—C9—C8	110.3 (2)
C5—C4—C3	120.5 (3)

O3—S1—N1—C1	−163.3 (2)	C1—C6—C7—C11	166.1 (3)
O4—S1—N1—C1	68.5 (2)	C5—C6—C7—C11	−9.2 (4)
C8—S1—N1—C1	−45.7 (2)	C6—C7—C8—C9	178.5 (2)
S1—N1—C1—C2	−149.9 (2)	C11—C7—C8—C9	−3.3 (4)
S1—N1—C1—C6	32.6 (3)	C6—C7—C8—S1	−6.1 (3)
N1—C1—C2—C3	−178.3 (3)	C11—C7—C8—S1	172.1 (2)
C6—C1—C2—C3	−0.8 (4)	O3—S1—C8—C7	145.0 (2)
C1—C2—C3—C4	−0.9 (5)	O4—S1—C8—C7	−84.1 (2)
C2—C3—C4—C5	2.1 (5)	N1—S1—C8—C7	32.2 (2)
C3—C4—C5—C6	−1.6 (4)	O3—S1—C8—C9	−39.2 (2)
C2—C1—C6—C5	1.3 (4)	O4—S1—C8—C9	91.8 (2)
N1—C1—C6—C5	178.8 (2)	N1—S1—C8—C9	−151.97 (19)
C2—C1—C6—C7	−174.3 (2)	C10—O2—C9—O1	−4.8 (5)
N1—C1—C6—C7	3.2 (4)	C10—O2—C9—C8	174.5 (2)
C4—C5—C6—C1	−0.1 (4)	C7—C8—C9—O1	−35.2 (5)
C4—C5—C6—C7	175.5 (2)	S1—C8—C9—O1	149.2 (3)
C1—C6—C7—C8	−15.6 (4)	C7—C8—C9—O2	145.5 (3)
C5—C6—C7—C8	169.1 (3)	S1—C8—C9—O2	−30.1 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11C···O1	0.96	2.24	2.986 (5)	133
N1—H1N···O4ⁱ	0.81 (4)	2.09 (4)	2.891 (3)	170 (4)
C4—H4···O3ⁱⁱ	0.93	2.55	3.427 (3)	158

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

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