organic compounds
Ethyl 2-[(3-methylquinoxalin-2-yl)sulfanyl]acetate
aLaboratory of Medicinal Chemistry, Faculty of Medicine and Pharmacy, Mohammed V University, Rabat, Morocco, bDepartment of Chemistry, Tulane University, New Orleans, LA 70118, USA, and cLaboratoire de Chimie Organique Heterocyclique URAC 21, Av. Ibn Battouta, BP, 1014, Faculte des Sciences, Universite Mohammed V, Rabat, Morocco
*Correspondence e-mail: mohcinemissioui@yahoo.com
In the title molecule, C13H14N2O2S, the dihedral angle between the pyrazine and benzene ring planes is 2.21 (5)°. The mean plane of the quinoxaline ring system is inclined to the sufanylacetate substituent by 81.74 (2)°. In the crystal, inversion-related C—H⋯N hydrogen bonds form dimers, which are linked into oblique stacks along the a-axis direction by C—H⋯O hydrogen bonds and π–π-stacking interactions.
Keywords: crystal structure; quinoxaline; thioacetate; hydrogen bonds; π–π stacking.
CCDC reference: 1590194
Structure description
Among the various classes of nitrogen et al., 2014). The chemistry of quinoxaline and its derivatives has attracted increasing attention because of their diverse pharmacological properties. These include use as cytotoxic, anti-inflammatory, antimicrobial, antioxidant, antifungal and antiviral agents (Ramli & Essassi, 2015). In light of these facts and as a continuation of our work on the synthesis of quinoxaline-2-thione derivatives in order to evaluate their pharmacological activity (Ramli et al., 2011, 2013a,b, 2017; Caleb et al., 2016), the title compound (Fig. 1) was synthesized and its structure is reported here.
quinoxaline derivatives display a broad spectrum of biological activity (RamliThe dihedral angle between the mean planes (r.m.s. deviation = 0.001 Å for each) of the N1/C1/C8/N2/C7/C2 and C2–C7 rings is 2.21 (5)°. The plane through all atoms of the methylquinoxaline ring system is inclined to the plane through the S1/O1/O2/C10–C13 atoms of the sulfanylacetate substituent by 81.74 (2)°.
In the crystal, centrosymmetric dimers form through inversion-related C6—H6⋯N2 hydrogen bonds with the mean plane of the dimer inclined at 69.15 (6)° to [001] (Table 1 and Fig. 2). The dimers are formed into oblique stacks extending along the a-axis direction by a combination of C10—H10B⋯O1 hydrogen bonds and π-stacking interactions between the C2–C7 ring of one molecule and an adjacent C1/N1/C2/C7/N2/C8 ring (Table 1 and Figs. 2 and 3). The dihedral angle between these planes is 2.12 (5)°, and the centroid–centroid distance is 3.7756 (6) Å.
Synthesis and crystallization
To a solution of 3-methylquinoxaline-2(1H)-thione (5. 67 mmol, 1 g) in 20 ml of DMF was added ethyl bromo acetate (5. 67 mmol), K2CO3 (5. 67 mmol) and a catalytic amount of tetrabutylammonium bromide. The mixture was stirred at room temperature for 4 h. Progress was monitored by TLC and, when complete, the solid material was removed by filtration and the solvent evaporated under vacuum. The solid product was purified by recrystallization from ethanol solution to afford colourless block-like crystals of the title compound (yield 70%).
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 1590194
https://doi.org/10.1107/S2414314617017631/sj4148sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617017631/sj4148Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314617017631/sj4148Isup3.cml
Data collection: APEX3 (Bruker, 2016); cell
SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016/6 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C13H14N2O2S | Z = 2 |
Mr = 262.32 | F(000) = 276 |
Triclinic, P1 | Dx = 1.360 Mg m−3 |
a = 4.8078 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.7314 (4) Å | Cell parameters from 7128 reflections |
c = 17.8011 (10) Å | θ = 2.3–29.2° |
α = 93.412 (1)° | µ = 0.25 mm−1 |
β = 94.564 (1)° | T = 100 K |
γ = 103.050 (1)° | Block, colourless |
V = 640.50 (6) Å3 | 0.24 × 0.19 × 0.14 mm |
Bruker SMART APEX CCD diffractometer | 3429 independent reflections |
Radiation source: fine-focus sealed tube | 2989 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
Detector resolution: 8.3333 pixels mm-1 | θmax = 29.2°, θmin = 2.3° |
φ and ω scans | h = −6→6 |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | k = −10→10 |
Tmin = 0.90, Tmax = 0.97 | l = −24→24 |
12471 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.036 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.106 | All H-atom parameters refined |
S = 1.13 | w = 1/[σ2(Fo2) + (0.0715P)2 + 0.0147P] where P = (Fo2 + 2Fc2)/3 |
3429 reflections | (Δ/σ)max < 0.001 |
219 parameters | Δρmax = 0.51 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, colllected at φ = 0.00, 90.00 and 180.00° and 2 sets of 800 frames, each of width 0.45° in φ, collected at ω = –30.00 and 210.00°. The scan time was 15 sec/frame. |
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. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
S1 | 0.36572 (5) | 0.83809 (3) | 0.22771 (2) | 0.01635 (10) | |
O1 | 0.77627 (17) | 0.92958 (11) | 0.37270 (5) | 0.02107 (19) | |
O2 | 0.48291 (17) | 0.75362 (11) | 0.44375 (4) | 0.02113 (19) | |
N1 | 0.62989 (18) | 0.57047 (11) | 0.23657 (5) | 0.01322 (19) | |
N2 | 0.77521 (19) | 0.59410 (12) | 0.08561 (5) | 0.01459 (19) | |
C1 | 0.5584 (2) | 0.68682 (14) | 0.19277 (6) | 0.0128 (2) | |
C2 | 0.7772 (2) | 0.45609 (14) | 0.20461 (6) | 0.0126 (2) | |
C3 | 0.8533 (2) | 0.32286 (14) | 0.24738 (6) | 0.0166 (2) | |
H3 | 0.787 (3) | 0.3094 (18) | 0.2980 (8) | 0.022 (3)* | |
C4 | 1.0070 (2) | 0.21126 (15) | 0.21664 (7) | 0.0183 (2) | |
H4 | 1.050 (3) | 0.128 (2) | 0.2451 (10) | 0.038 (4)* | |
C5 | 1.0920 (2) | 0.22905 (15) | 0.14311 (6) | 0.0184 (2) | |
H5 | 1.194 (4) | 0.148 (3) | 0.1226 (11) | 0.049 (5)* | |
C6 | 1.0180 (2) | 0.35609 (15) | 0.09980 (6) | 0.0168 (2) | |
H6 | 1.076 (3) | 0.3690 (19) | 0.0499 (8) | 0.023 (3)* | |
C7 | 0.8555 (2) | 0.47049 (14) | 0.12995 (6) | 0.0135 (2) | |
C8 | 0.6262 (2) | 0.69891 (14) | 0.11535 (6) | 0.0141 (2) | |
C9 | 0.5263 (3) | 0.82984 (16) | 0.06723 (6) | 0.0194 (2) | |
H9A | 0.314 (4) | 0.817 (2) | 0.0642 (10) | 0.040 (4)* | |
H9B | 0.594 (3) | 0.949 (2) | 0.0911 (9) | 0.031 (4)* | |
H9C | 0.588 (3) | 0.820 (2) | 0.0185 (9) | 0.034 (4)* | |
C10 | 0.3034 (2) | 0.76191 (15) | 0.31903 (6) | 0.0160 (2) | |
H10A | 0.251 (3) | 0.637 (2) | 0.3185 (8) | 0.025 (4)* | |
H10B | 0.145 (3) | 0.8045 (19) | 0.3360 (8) | 0.025 (4)* | |
C11 | 0.5520 (2) | 0.82636 (14) | 0.37907 (6) | 0.0158 (2) | |
C12 | 0.6999 (3) | 0.80583 (19) | 0.50825 (7) | 0.0264 (3) | |
H12A | 0.860 (3) | 0.764 (2) | 0.4947 (9) | 0.033 (4)* | |
H12B | 0.751 (3) | 0.938 (2) | 0.5145 (8) | 0.026 (4)* | |
C13 | 0.5698 (4) | 0.7234 (2) | 0.57545 (8) | 0.0343 (3) | |
H13A | 0.699 (4) | 0.756 (2) | 0.6176 (10) | 0.041 (5)* | |
H13B | 0.539 (4) | 0.601 (3) | 0.5704 (12) | 0.063 (6)* | |
H13C | 0.389 (4) | 0.768 (2) | 0.5829 (10) | 0.050 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.01682 (16) | 0.01777 (16) | 0.01610 (15) | 0.00755 (11) | 0.00186 (10) | 0.00039 (10) |
O1 | 0.0150 (4) | 0.0250 (4) | 0.0216 (4) | 0.0024 (3) | 0.0022 (3) | −0.0026 (3) |
O2 | 0.0207 (4) | 0.0253 (4) | 0.0158 (4) | 0.0030 (3) | −0.0007 (3) | 0.0010 (3) |
N1 | 0.0118 (4) | 0.0152 (4) | 0.0127 (4) | 0.0029 (3) | 0.0018 (3) | 0.0013 (3) |
N2 | 0.0131 (4) | 0.0170 (4) | 0.0129 (4) | 0.0019 (3) | 0.0011 (3) | 0.0015 (3) |
C1 | 0.0106 (5) | 0.0140 (5) | 0.0132 (5) | 0.0023 (4) | 0.0005 (4) | 0.0001 (4) |
C2 | 0.0113 (4) | 0.0139 (5) | 0.0122 (5) | 0.0019 (4) | 0.0010 (4) | 0.0010 (3) |
C3 | 0.0172 (5) | 0.0173 (5) | 0.0160 (5) | 0.0045 (4) | 0.0029 (4) | 0.0035 (4) |
C4 | 0.0202 (5) | 0.0150 (5) | 0.0207 (5) | 0.0064 (4) | 0.0000 (4) | 0.0030 (4) |
C5 | 0.0172 (5) | 0.0177 (5) | 0.0208 (5) | 0.0064 (4) | 0.0020 (4) | −0.0029 (4) |
C6 | 0.0155 (5) | 0.0193 (5) | 0.0147 (5) | 0.0031 (4) | 0.0016 (4) | −0.0020 (4) |
C7 | 0.0122 (5) | 0.0152 (5) | 0.0122 (5) | 0.0011 (4) | 0.0010 (4) | 0.0004 (4) |
C8 | 0.0127 (5) | 0.0156 (5) | 0.0130 (5) | 0.0017 (4) | −0.0001 (4) | 0.0015 (4) |
C9 | 0.0217 (6) | 0.0221 (6) | 0.0162 (5) | 0.0078 (5) | 0.0013 (4) | 0.0053 (4) |
C10 | 0.0119 (5) | 0.0204 (6) | 0.0158 (5) | 0.0039 (4) | 0.0026 (4) | −0.0012 (4) |
C11 | 0.0161 (5) | 0.0173 (5) | 0.0159 (5) | 0.0086 (4) | 0.0027 (4) | −0.0027 (4) |
C12 | 0.0250 (6) | 0.0356 (7) | 0.0178 (6) | 0.0087 (5) | −0.0046 (5) | −0.0014 (5) |
C13 | 0.0503 (9) | 0.0335 (8) | 0.0195 (6) | 0.0115 (7) | −0.0006 (6) | 0.0034 (5) |
S1—C1 | 1.7626 (10) | C5—H5 | 0.954 (19) |
S1—C10 | 1.7863 (11) | C6—C7 | 1.4153 (14) |
O1—C11 | 1.2057 (13) | C6—H6 | 0.956 (14) |
O2—C11 | 1.3438 (13) | C8—C9 | 1.4986 (14) |
O2—C12 | 1.4607 (14) | C9—H9A | 1.001 (17) |
N1—C1 | 1.3100 (13) | C9—H9B | 0.966 (16) |
N1—C2 | 1.3762 (13) | C9—H9C | 0.944 (16) |
N2—C8 | 1.3121 (13) | C10—C11 | 1.5111 (15) |
N2—C7 | 1.3760 (13) | C10—H10A | 0.938 (15) |
C1—C8 | 1.4448 (14) | C10—H10B | 0.959 (14) |
C2—C3 | 1.4121 (14) | C12—C13 | 1.5029 (19) |
C2—C7 | 1.4138 (14) | C12—H12A | 0.945 (16) |
C3—C4 | 1.3734 (15) | C12—H12B | 0.997 (16) |
C3—H3 | 0.983 (14) | C13—H13A | 0.921 (18) |
C4—C5 | 1.4071 (16) | C13—H13B | 0.92 (2) |
C4—H4 | 0.892 (18) | C13—H13C | 1.02 (2) |
C5—C6 | 1.3748 (16) | ||
C1—S1—C10 | 100.96 (5) | C8—C9—H9A | 113.1 (10) |
C11—O2—C12 | 115.87 (9) | C8—C9—H9B | 110.2 (9) |
C1—N1—C2 | 115.99 (9) | H9A—C9—H9B | 101.0 (13) |
C8—N2—C7 | 117.64 (9) | C8—C9—H9C | 109.9 (10) |
N1—C1—C8 | 123.63 (9) | H9A—C9—H9C | 110.8 (13) |
N1—C1—S1 | 119.73 (8) | H9B—C9—H9C | 111.5 (13) |
C8—C1—S1 | 116.64 (8) | C11—C10—S1 | 114.95 (8) |
N1—C2—C3 | 119.39 (9) | C11—C10—H10A | 107.2 (9) |
N1—C2—C7 | 121.19 (9) | S1—C10—H10A | 113.0 (9) |
C3—C2—C7 | 119.42 (9) | C11—C10—H10B | 106.9 (9) |
C4—C3—C2 | 119.76 (10) | S1—C10—H10B | 108.0 (9) |
C4—C3—H3 | 121.7 (8) | H10A—C10—H10B | 106.2 (12) |
C2—C3—H3 | 118.5 (8) | O1—C11—O2 | 123.78 (10) |
C3—C4—C5 | 120.75 (10) | O1—C11—C10 | 127.14 (10) |
C3—C4—H4 | 117.3 (11) | O2—C11—C10 | 109.05 (9) |
C5—C4—H4 | 121.9 (11) | O2—C12—C13 | 107.04 (11) |
C6—C5—C4 | 120.79 (10) | O2—C12—H12A | 106.0 (10) |
C6—C5—H5 | 120.1 (12) | C13—C12—H12A | 113.7 (10) |
C4—C5—H5 | 119.0 (12) | O2—C12—H12B | 107.2 (9) |
C5—C6—C7 | 119.34 (10) | C13—C12—H12B | 112.8 (9) |
C5—C6—H6 | 121.1 (9) | H12A—C12—H12B | 109.7 (13) |
C7—C6—H6 | 119.6 (9) | C12—C13—H13A | 109.5 (11) |
N2—C7—C2 | 121.00 (9) | C12—C13—H13B | 111.4 (13) |
N2—C7—C6 | 119.11 (9) | H13A—C13—H13B | 103.8 (16) |
C2—C7—C6 | 119.89 (10) | C12—C13—H13C | 108.0 (10) |
N2—C8—C1 | 120.45 (9) | H13A—C13—H13C | 110.2 (15) |
N2—C8—C9 | 118.66 (9) | H13B—C13—H13C | 113.9 (17) |
C1—C8—C9 | 120.88 (9) | ||
C2—N1—C1—C8 | −0.08 (15) | C3—C2—C7—C6 | −2.32 (15) |
C2—N1—C1—S1 | 179.30 (7) | C5—C6—C7—N2 | −178.20 (10) |
C10—S1—C1—N1 | −4.60 (10) | C5—C6—C7—C2 | 1.54 (16) |
C10—S1—C1—C8 | 174.83 (8) | C7—N2—C8—C1 | 1.87 (15) |
C1—N1—C2—C3 | −177.86 (9) | C7—N2—C8—C9 | −177.65 (9) |
C1—N1—C2—C7 | 2.65 (15) | N1—C1—C8—N2 | −2.29 (16) |
N1—C2—C3—C4 | −178.24 (10) | S1—C1—C8—N2 | 178.31 (8) |
C7—C2—C3—C4 | 1.26 (16) | N1—C1—C8—C9 | 177.21 (9) |
C2—C3—C4—C5 | 0.57 (17) | S1—C1—C8—C9 | −2.19 (14) |
C3—C4—C5—C6 | −1.36 (17) | C1—S1—C10—C11 | 81.32 (9) |
C4—C5—C6—C7 | 0.29 (17) | C12—O2—C11—O1 | −0.45 (16) |
C8—N2—C7—C2 | 0.66 (15) | C12—O2—C11—C10 | −178.80 (9) |
C8—N2—C7—C6 | −179.60 (9) | S1—C10—C11—O1 | 4.50 (15) |
N1—C2—C7—N2 | −3.08 (16) | S1—C10—C11—O2 | −177.22 (7) |
C3—C2—C7—N2 | 177.42 (9) | C11—O2—C12—C13 | 175.03 (10) |
N1—C2—C7—C6 | 177.18 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6···N2i | 0.956 (14) | 2.584 (14) | 3.5398 (15) | 179.1 (12) |
C10—H10B···O1ii | 0.959 (14) | 2.320 (15) | 3.2770 (14) | 175.2 (12) |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x−1, y, z. |
Acknowledgements
JTM thanks Tulane University for support of the Tulane Crystallography Laboratory.
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