organic compounds
Ethyl 2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-yl)acetate
aLaboratoire de Chimie Organique Hétérocyclique, Centre de Recherche des Sciences des Médicaments, URAC 21, Pôle de Compétence Pharmacochimie, Av Ibn Battouta, BP 1014, Faculté des Sciences, Université Mohammed V, Rabat, Morocco, bLaboratory of Medicinal Chemistry, Faculty of Medicine and Pharmacy, University Mohammed V, Rabat, Morocco, and cDepartment of Chemistry, Tulane University, New Orleans, LA 70118, USA
*Correspondence e-mail: ab.nadeem2018@gmail.com
In the title compound, C12H14N2O3, the conformation of the ester substituent is partially determined by an intramolecular N—H⋯O hydrogen bond. The crystal packing consists of layers parallel to (12) held together by N—H⋯O and C—H⋯O hydrogen bonds. The CH/NH portion of the heterocyclic ring is disordered over two sites in a 0.930 (5):0.070 (5) ratio with the disorder also extending to the O atom involved in the intramolecular N—H⋯O hydrogen bond.
Keywords: crystal structure; hydrogen bond; quinoxaline.
CCDC reference: 1837851
Structure description
Quinoxaline derivatives exhibit a variety of biological activities including anticancer (Lindsley et al., 2005; Carta et al., 2006), antidiabetic (Gupta et al., 2005), antimicrobial (Singh et al., 2010), anti-inflammatory (El-Sabbagh et al., 2009) and anti-malarial (Guillon et al., 2004). Moreover, they are used as fungicides, insecticides and herbicides (Sakata et al., 1988). The numerous applications of quinoxalines has prompted researchers to develop efficient methods to synthesize new derivatives likely to present interesting activities (Ramli et al., 2018). We report in this work the synthesis and of the title compound (Fig. 1).
A puckering analysis of the heterocyclic ring yielded the parameters Q = 0.421 (3) Å, θ = 119.1 (4)° and φ = 34.3 (4)° for the major component. The orientation of the ester substituent is partially determined by the intramolecular N2—H2A⋯O2 hydrogen bond. In the crystal, pairs of N1—H1A⋯O1 hydrogen bonds form inversion dimers, which are linked into chains by inversion-related C11—H11B⋯O2 hydrogen bonds. The chains are formed into layers parallel to (12) by C3—H3⋯O3 hydrogen bonds (Table 1 and Fig. 2). The layers are linked to one another by C8—H8⋯O1 and C9—H9A⋯O2 hydrogen bonds (Table 1 and Figs. 3 and 4).
Synthesis and crystallization
A mixture of ethyl-2-(3-oxo-3,4-dihydroquinoxalin-2-yl)acetate (1 g) with Pd/C catalyst in ethanol was stirred for 10 h in presence of hydrogen. The reaction mixture was filtered and the solvent was removed under pressure. The residue obtained was recrystallized from ethanol to afford the title molecule as yellow crystals.
Refinement
Crystal data, data collection and structure . The C8/N2 portion of the heterocyclic ring is disordered over two sites in a 0.930 (5):0.070 (5) ratio with the disorder also extending to O2. The two components were refined subject to restraints that their geometries be comparable and the affected hydrogen atoms were included as riding contributions in idealized positions. The two noticeable residual peaks in the final difference map are attributed to errors resulting from neglect of the other minor components of the crystal.
details are summarized in Table 2
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Structural data
CCDC reference: 1837851
https://doi.org/10.1107/S2414314618005965/zq4028sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618005965/zq4028Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314618005965/zq4028Isup3.cdx
Supporting information file. DOI: https://doi.org/10.1107/S2414314618005965/zq4028Isup4.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: SHELXL2018 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C12H14N2O3 | Z = 2 |
Mr = 234.25 | F(000) = 248 |
Triclinic, P1 | Dx = 1.385 Mg m−3 |
a = 4.8082 (18) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.260 (3) Å | Cell parameters from 2025 reflections |
c = 14.413 (6) Å | θ = 2.8–28.2° |
α = 84.072 (7)° | µ = 0.10 mm−1 |
β = 81.473 (5)° | T = 100 K |
γ = 85.140 (5)° | Block, yellow |
V = 561.7 (4) Å3 | 0.19 × 0.14 × 0.13 mm |
Bruker SMART APEX CCD diffractometer | 9489 independent reflections |
Radiation source: fine-focus sealed tube | 4504 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.028 |
Detector resolution: 8.3333 pixels mm-1 | θmax = 28.3°, θmin = 1.4° |
ω scans | h = −6→6 |
Absorption correction: multi-scan (TWINABS; Sheldrick, 2009) | k = −10→10 |
Tmin = 0.98, Tmax = 0.99 | l = −19→19 |
9489 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)] = 0.061 | Hydrogen site location: mixed |
wR(F2) = 0.213 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | w = 1/[σ2(Fo2) + (0.1018P)2] where P = (Fo2 + 2Fc2)/3 |
9489 reflections | (Δ/σ)max < 0.001 |
205 parameters | Δρmax = 1.16 e Å−3 |
4 restraints | Δρmin = −0.82 e Å−3 |
Experimental. The diffraction data were collected in three sets of 363 frames (0.5° width in ω) at φ = 0, 120 and 240°. A scan time of 60 sec/frame was used. Analysis of 564 reflections having I/σ(I) > 12 and chosen from the full data set with CELL_NOW (Sheldrick, 2008) showed the crystal to belong to the triclinic system and to consist of one major component and several minor components rotated from the former by ca. 7° about non-special axes. After several trials, it was decided to treat the crystal as having one major and one minor component rotsted from the first by 7.3° about the real axis 1, -0.42, 0. The raw data were processed using the multi-component version of SAINT under control of the two-component orientation file generated by CELL_NOW. |
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. Refined as a 2-component twin. The heterocyclic ring is disordered over two conformations in a 93:7 ratio which also affects the position of O2. The two components were refined subject to restraints that their geometries be comparable and the affected hydrogen atoms were included as riding contributions in idealized positions. The two noticeable residual peaks in the final difference map are attributed to errors resulting from neglect of the other minor components of the crystal. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1 | −0.0170 (4) | 0.3173 (2) | 0.08301 (11) | 0.0292 (5) | |
O2 | 0.4815 (5) | 0.1288 (3) | 0.36066 (16) | 0.0296 (6) | 0.930 (5) |
O2A | 0.370 (7) | 0.165 (3) | 0.3836 (18) | 0.0296 (6) | 0.070 (5) |
O3 | 0.1574 (3) | −0.0537 (2) | 0.36597 (11) | 0.0265 (5) | |
N1 | 0.2161 (4) | 0.5434 (3) | 0.08754 (15) | 0.0246 (5) | |
H1A | 0.151 (6) | 0.589 (3) | 0.037 (2) | 0.042 (8)* | |
N2 | 0.3448 (6) | 0.4290 (3) | 0.26056 (15) | 0.0257 (7) | 0.930 (5) |
H2A | 0.434112 | 0.380595 | 0.308727 | 0.031* | 0.930 (5) |
N2A | 0.455 (6) | 0.4000 (8) | 0.236 (3) | 0.0257 (7) | 0.070 (5) |
H2AA | 0.529600 | 0.386739 | 0.290485 | 0.031* | 0.070 (5) |
C1 | 0.4714 (5) | 0.5695 (3) | 0.21646 (17) | 0.0253 (6) | |
C2 | 0.6484 (6) | 0.6542 (3) | 0.25833 (18) | 0.0277 (6) | |
H2 | 0.707 (6) | 0.607 (3) | 0.3173 (19) | 0.029 (7)* | |
C3 | 0.7476 (6) | 0.8000 (3) | 0.21482 (19) | 0.0300 (6) | |
H3 | 0.867 (6) | 0.855 (3) | 0.2458 (19) | 0.032 (7)* | |
C4 | 0.6712 (6) | 0.8619 (3) | 0.12873 (19) | 0.0297 (6) | |
H4 | 0.743 (6) | 0.962 (3) | 0.1001 (18) | 0.033 (7)* | |
C5 | 0.4964 (6) | 0.7775 (3) | 0.08525 (19) | 0.0280 (6) | |
H5 | 0.445 (6) | 0.816 (3) | 0.026 (2) | 0.036 (8)* | |
C6 | 0.3965 (5) | 0.6312 (3) | 0.12848 (17) | 0.0234 (6) | |
C7 | 0.1471 (5) | 0.3917 (3) | 0.11900 (16) | 0.0245 (6) | |
C8 | 0.3030 (7) | 0.3082 (3) | 0.19800 (18) | 0.0240 (7) | 0.930 (5) |
H8 | 0.492195 | 0.263176 | 0.169224 | 0.029* | 0.930 (5) |
C9 | 0.1434 (5) | 0.1686 (3) | 0.25015 (17) | 0.0257 (6) | 0.930 (5) |
H9A | −0.049192 | 0.211036 | 0.274807 | 0.031* | 0.930 (5) |
H9B | 0.125712 | 0.088460 | 0.205156 | 0.031* | 0.930 (5) |
C8A | 0.181 (6) | 0.3479 (12) | 0.224 (3) | 0.0240 (7) | 0.070 (5) |
H8A | 0.031427 | 0.412289 | 0.262872 | 0.029* | 0.070 (5) |
C9A | 0.1434 (5) | 0.1686 (3) | 0.25015 (17) | 0.0257 (6) | 0.070 (5) |
H9A1 | −0.061579 | 0.155281 | 0.264919 | 0.031* | 0.070 (5) |
H9A2 | 0.213338 | 0.110327 | 0.193641 | 0.031* | 0.070 (5) |
C10 | 0.2804 (5) | 0.0826 (3) | 0.33062 (17) | 0.0245 (6) | |
C11 | 0.2761 (6) | −0.1435 (3) | 0.44557 (18) | 0.0275 (6) | |
H11A | 0.480 (6) | −0.166 (3) | 0.4238 (17) | 0.028 (7)* | |
H11B | 0.251 (5) | −0.072 (3) | 0.4957 (17) | 0.021 (6)* | |
C12 | 0.1264 (7) | −0.2975 (4) | 0.4700 (2) | 0.0343 (7) | |
H12A | 0.205 (6) | −0.360 (3) | 0.523 (2) | 0.042 (8)* | |
H12B | 0.153 (6) | −0.359 (3) | 0.416 (2) | 0.041 (8)* | |
H12C | −0.079 (7) | −0.271 (3) | 0.491 (2) | 0.048 (9)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0317 (10) | 0.0317 (11) | 0.0274 (10) | −0.0096 (8) | −0.0131 (8) | 0.0007 (7) |
O2 | 0.0261 (12) | 0.0338 (12) | 0.0317 (12) | −0.0077 (10) | −0.0134 (10) | 0.0021 (9) |
O2A | 0.0261 (12) | 0.0338 (12) | 0.0317 (12) | −0.0077 (10) | −0.0134 (10) | 0.0021 (9) |
O3 | 0.0274 (10) | 0.0273 (10) | 0.0264 (9) | −0.0055 (8) | −0.0115 (7) | 0.0038 (7) |
N1 | 0.0268 (12) | 0.0270 (12) | 0.0218 (11) | −0.0045 (9) | −0.0103 (9) | 0.0010 (9) |
N2 | 0.0304 (16) | 0.0263 (12) | 0.0222 (13) | −0.0056 (11) | −0.0102 (10) | 0.0010 (9) |
N2A | 0.0304 (16) | 0.0263 (12) | 0.0222 (13) | −0.0056 (11) | −0.0102 (10) | 0.0010 (9) |
C1 | 0.0261 (13) | 0.0239 (14) | 0.0269 (13) | −0.0022 (10) | −0.0076 (10) | −0.0019 (10) |
C2 | 0.0296 (14) | 0.0290 (15) | 0.0275 (13) | −0.0040 (11) | −0.0112 (11) | −0.0040 (11) |
C3 | 0.0277 (14) | 0.0302 (15) | 0.0356 (15) | −0.0040 (11) | −0.0102 (11) | −0.0096 (11) |
C4 | 0.0299 (14) | 0.0237 (14) | 0.0360 (15) | −0.0065 (11) | −0.0049 (11) | −0.0011 (11) |
C5 | 0.0293 (14) | 0.0283 (15) | 0.0273 (13) | −0.0037 (11) | −0.0081 (11) | 0.0005 (11) |
C6 | 0.0207 (13) | 0.0240 (13) | 0.0268 (13) | −0.0026 (10) | −0.0063 (10) | −0.0033 (10) |
C7 | 0.0234 (13) | 0.0286 (14) | 0.0228 (12) | −0.0043 (10) | −0.0064 (10) | −0.0020 (10) |
C8 | 0.0243 (16) | 0.0261 (15) | 0.0237 (14) | −0.0057 (12) | −0.0087 (11) | −0.0018 (11) |
C9 | 0.0259 (13) | 0.0265 (14) | 0.0266 (13) | −0.0056 (11) | −0.0103 (10) | 0.0008 (10) |
C8A | 0.0243 (16) | 0.0261 (15) | 0.0237 (14) | −0.0057 (12) | −0.0087 (11) | −0.0018 (11) |
C9A | 0.0259 (13) | 0.0265 (14) | 0.0266 (13) | −0.0056 (11) | −0.0103 (10) | 0.0008 (10) |
C10 | 0.0232 (13) | 0.0264 (14) | 0.0249 (12) | −0.0031 (10) | −0.0056 (10) | −0.0028 (10) |
C11 | 0.0284 (15) | 0.0296 (15) | 0.0259 (13) | −0.0018 (11) | −0.0121 (11) | 0.0016 (11) |
C12 | 0.0349 (17) | 0.0338 (17) | 0.0353 (16) | −0.0065 (13) | −0.0124 (13) | 0.0051 (13) |
O1—C7 | 1.240 (3) | C4—H4 | 0.95 (3) |
O2—C10 | 1.221 (3) | C5—C6 | 1.391 (3) |
O2A—C10 | 1.221 (5) | C5—H5 | 0.94 (3) |
O3—C10 | 1.335 (3) | C7—C8 | 1.529 (4) |
O3—C11 | 1.463 (3) | C7—C8A | 1.54 (4) |
N1—C7 | 1.339 (3) | C8—C9 | 1.511 (3) |
N1—C6 | 1.405 (3) | C8—H8 | 1.0000 |
N1—H1A | 0.87 (3) | C9—C10 | 1.503 (3) |
N2—C1 | 1.405 (3) | C9—H9A | 0.9900 |
N2—C8 | 1.457 (3) | C9—H9B | 0.9900 |
N2—H2A | 0.9101 | C8A—C9A | 1.511 (5) |
N2A—C1 | 1.405 (5) | C8A—H8A | 1.0000 |
N2A—C8A | 1.457 (5) | C9A—C10 | 1.503 (3) |
N2A—H2AA | 0.900 | C9A—H9A1 | 0.9900 |
C1—C2 | 1.385 (3) | C9A—H9A2 | 0.9900 |
C1—C6 | 1.403 (3) | C11—C12 | 1.499 (4) |
C2—C3 | 1.387 (4) | C11—H11A | 0.99 (3) |
C2—H2 | 0.97 (3) | C11—H11B | 0.97 (2) |
C3—C4 | 1.382 (4) | C12—H12A | 0.98 (3) |
C3—H3 | 0.95 (3) | C12—H12B | 0.96 (3) |
C4—C5 | 1.389 (4) | C12—H12C | 1.00 (3) |
C10—O3—C11 | 115.31 (18) | C9—C8—H8 | 108.4 |
C7—N1—C6 | 124.1 (2) | C7—C8—H8 | 108.4 |
C7—N1—H1A | 117.8 (19) | C10—C9—C8 | 113.8 (2) |
C6—N1—H1A | 118.0 (19) | C10—C9—H9A | 108.8 |
C1—N2—C8 | 115.6 (2) | C8—C9—H9A | 108.8 |
C1—N2—H2A | 112.6 | C10—C9—H9B | 108.8 |
C8—N2—H2A | 110.1 | C8—C9—H9B | 108.8 |
C1—N2A—C8A | 112.4 (11) | H9A—C9—H9B | 107.7 |
C1—N2A—H2AA | 98.5 | N2A—C8A—C9A | 114.8 (11) |
C8A—N2A—H2AA | 125.0 | N2A—C8A—C7 | 107 (3) |
C2—C1—C6 | 119.3 (2) | C9A—C8A—C7 | 110 (2) |
C2—C1—N2 | 123.2 (2) | N2A—C8A—H8A | 108.4 |
C6—C1—N2 | 117.3 (2) | C9A—C8A—H8A | 108.4 |
C2—C1—N2A | 121.8 (13) | C7—C8A—H8A | 108.4 |
C6—C1—N2A | 113.8 (15) | C10—C9A—C8A | 119.1 (12) |
C1—C2—C3 | 120.6 (2) | C10—C9A—H9A1 | 107.5 |
C1—C2—H2 | 118.3 (15) | C8A—C9A—H9A1 | 107.5 |
C3—C2—H2 | 121.0 (15) | C10—C9A—H9A2 | 107.5 |
C4—C3—C2 | 120.1 (2) | C8A—C9A—H9A2 | 107.5 |
C4—C3—H3 | 121.5 (16) | H9A1—C9A—H9A2 | 107.0 |
C2—C3—H3 | 118.4 (16) | O2—C10—O3 | 123.0 (2) |
C3—C4—C5 | 120.0 (2) | O2A—C10—O3 | 119.3 (15) |
C3—C4—H4 | 118.4 (17) | O2A—C10—C9A | 118.3 (15) |
C5—C4—H4 | 121.5 (16) | O3—C10—C9A | 111.9 (2) |
C4—C5—C6 | 120.1 (2) | O2—C10—C9 | 125.1 (2) |
C4—C5—H5 | 121.4 (17) | O3—C10—C9 | 111.9 (2) |
C6—C5—H5 | 118.4 (17) | O3—C11—C12 | 107.2 (2) |
C5—C6—C1 | 119.8 (2) | O3—C11—H11A | 106.5 (14) |
C5—C6—N1 | 121.9 (2) | C12—C11—H11A | 111.7 (14) |
C1—C6—N1 | 118.3 (2) | O3—C11—H11B | 106.9 (15) |
O1—C7—N1 | 123.1 (2) | C12—C11—H11B | 114.0 (14) |
O1—C7—C8 | 121.0 (2) | H11A—C11—H11B | 110 (2) |
N1—C7—C8 | 115.7 (2) | C11—C12—H12A | 108.3 (17) |
O1—C7—C8A | 119.4 (6) | C11—C12—H12B | 109.2 (17) |
N1—C7—C8A | 112.8 (5) | H12A—C12—H12B | 111 (2) |
N2—C8—C9 | 111.9 (2) | C11—C12—H12C | 110.0 (16) |
N2—C8—C7 | 109.1 (2) | H12A—C12—H12C | 107 (2) |
C9—C8—C7 | 110.6 (2) | H12B—C12—H12C | 111 (3) |
N2—C8—H8 | 108.4 | ||
C8—N2—C1—C2 | −147.1 (3) | C1—N2—C8—C7 | −52.3 (4) |
C8—N2—C1—C6 | 37.4 (4) | O1—C7—C8—N2 | −148.2 (2) |
C8A—N2A—C1—C2 | 153 (3) | N1—C7—C8—N2 | 36.6 (3) |
C8A—N2A—C1—C6 | −53 (3) | O1—C7—C8—C9 | −24.7 (3) |
C6—C1—C2—C3 | 1.1 (4) | N1—C7—C8—C9 | 160.1 (2) |
N2—C1—C2—C3 | −174.4 (2) | N2—C8—C9—C10 | −56.8 (3) |
N2A—C1—C2—C3 | 154.5 (17) | C7—C8—C9—C10 | −178.6 (2) |
C1—C2—C3—C4 | −0.3 (4) | C1—N2A—C8A—C9A | −176 (2) |
C2—C3—C4—C5 | −0.5 (4) | C1—N2A—C8A—C7 | 62 (3) |
C3—C4—C5—C6 | 0.4 (4) | O1—C7—C8A—N2A | 157.1 (11) |
C4—C5—C6—C1 | 0.4 (4) | N1—C7—C8A—N2A | −46.4 (19) |
C4—C5—C6—N1 | 179.1 (2) | O1—C7—C8A—C9A | 32 (2) |
C2—C1—C6—C5 | −1.1 (4) | N1—C7—C8A—C9A | −171.4 (12) |
N2—C1—C6—C5 | 174.6 (2) | N2A—C8A—C9A—C10 | 34 (4) |
N2A—C1—C6—C5 | −156.6 (13) | C7—C8A—C9A—C10 | 154.6 (10) |
C2—C1—C6—N1 | −179.8 (2) | C11—O3—C10—O2 | 1.4 (4) |
N2—C1—C6—N1 | −4.1 (3) | C11—O3—C10—O2A | −35 (2) |
N2A—C1—C6—N1 | 24.7 (14) | C11—O3—C10—C9A | −179.2 (2) |
C7—N1—C6—C5 | 169.9 (2) | C11—O3—C10—C9 | −179.2 (2) |
C7—N1—C6—C1 | −11.4 (4) | C8A—C9A—C10—O2A | 14 (2) |
C6—N1—C7—O1 | 178.5 (2) | C8A—C9A—C10—O3 | 159.0 (17) |
C6—N1—C7—C8 | −6.4 (3) | C8—C9—C10—O2 | 8.6 (4) |
C6—N1—C7—C8A | 23.1 (14) | C8—C9—C10—O3 | −170.8 (2) |
C1—N2—C8—C9 | −175.0 (2) | C10—O3—C11—C12 | −175.7 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1i | 0.87 (3) | 1.99 (4) | 2.866 (3) | 177 (3) |
N2—H2A···O2 | 0.91 | 2.14 | 2.816 (3) | 130 |
C3—H3···O3ii | 0.95 (3) | 2.59 (3) | 3.508 (3) | 165 (2) |
C8—H8···O1iii | 1.00 | 2.55 | 3.443 (4) | 148 |
C9—H9A···O2iv | 0.99 | 2.52 | 3.367 (4) | 144 |
C11—H11B···O2v | 0.97 (2) | 2.58 (3) | 3.199 (3) | 121.9 (18) |
Symmetry codes: (i) −x, −y+1, −z; (ii) x+1, y+1, z; (iii) x+1, y, z; (iv) x−1, y, z; (v) −x+1, −y, −z+1. |
Acknowledgements
JTM thanks Tulane University for support of the Tulane Crystallography Laboratory.
References
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