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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 12| December 2011| Page o3332
https://doi.org/10.1107/S1600536811047994

N-(4-Chloro-2-nitro­phen­yl)-5-methyl­isoxazole-4-carboxamide

De-Cai Wang,a* Liang-Cheng Huang,a Zhu-Yun Liu,a Ping Weia and Ping-Kai Ou-yanga

aState Key Laboratory of Materials-Oriented Chemical Engineering, School of Pharmaceutical Sciences, Nanjing University of Technology, Xinmofan Road No. 5 Nanjing, Nanjing 210009, People's Republic of China.
*Correspondence e-mail: dc_wang@hotmail.com

(Received 4 November 2011; accepted 11 November 2011; online 16 November 2011)

In the title compound, C11H8ClN3O4, the dihedral angle between benzene and isoxazole rings is 9.92 (1) °. The nitro group is almost coplanar with the benzene ring with an O—N—C—C torsion angle of 8.4 (3)°. The mol­ecular conformation is stabilized by an intra­molecular N—H⋯O hydrogen bond, closing a six-membered ring.

Related literature

For applications of leflunomide [systematic name: 5-methyl-N-[4-(trifluoro­meth­yl) phen­yl]-isoxazole-4-carboxamide] in the treatment of rheumatoid arthritis, see: Shaw et al. (2011[Shaw, J. J., Chen, B., Wooley, P., Palfey, B., Lee, A. R., Huang, W. H. & Zeng, D. (2011). Am. J. Biomed. Sci. 3, 218-227.]); Schattenkirchner (2000[Schattenkirchner, M. (2000). Immunopharmacology, 47, 291-298.]). The title compound was synthesized as an immunomodulating leflunomide analog; for another immunomodulating leflunomide analog, see: Huang et al. (2003[Huang, W. H., Yang, C. L., LEE, A. R. & Chiu, H. F. (2003). Chem. Pharm. Bull. 51, 313-314.]).

[Scheme 1]

Experimental

Crystal data

  • C11H8ClN3O4

  • Mr = 281.65

  • Monoclinic, P 21 /c

  • a = 5.3870 (11) Å

  • b = 23.537 (5) Å

  • c = 9.4600 (19) Å

  • β = 99.86 (3)°

  • V = 1181.8 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.34 mm−1

  • T = 293 K

  • 0.30 × 0.20 × 0.10 mm
Data collection

  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: ψ scan (North et al., 1968[North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.]) Tmin = 0.905, Tmax = 0.967

  • 4645 measured reflections

  • 2121 independent reflections

  • 1558 reflections with I > 2σ(I)

  • Rint = 0.044

  • 3 standard reflections every 200 reflections intensity decay: 1%
Refinement

  • R[F2 > 2σ(F2)] = 0.042

  • wR(F2) = 0.143

  • S = 1.02

  • 2121 reflections

  • 174 parameters

  • H-atom parameters constrained

  • Δρmax = 0.18 e Å−3

  • Δρmin = −0.22 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N2—H2B⋯O2 0.86 1.94 2.629 (3) 136

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536811047994/ld2035sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811047994/ld2035Isup2.hkl

checkCIF report


Comment top

Leflunomide is one of the most effective isoxazole-containing disease-modifying drugs for treating rheumatoid arthritis(Shaw et al., 2011; Schattenkirchner, 2000). Many leflunomide analogs have been synthesized and exhibit potent immunomodulating effect (Huang, et al., 2003). The title compound, 5-methyl-N-(4-chloro-2-nitrophenyl)isoxazole-4-carboxamide (I), was synthesized as a novel and potent immunomodulating leflunomide analog. We report herein its crystal structure. The molecular structure of the title compound is shown in Fig. 1. The nitro group is approximately coplanar with the benzene ring, as indicated by the torsion angle O1—N1—C5—C4 of 8.4 (3)°. The amide group is also coplanar with the benzene and isoxazole rings [torsion angles N2—C7—C8—C9 and C7—N2—C6—C1 are -8.9 (4) and -3.1 (4)°], respectively. The molecular conformation is stabilized by an intra-molecular N—H···O hydrogen bond (Table 1). In the crystal, infinite zigzag chain are formed via short inter-molecular Cl···O contacts of 3.089 (3) Å.

Related literature top

For applications of leflunomide [systematic name: 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4-carboxamide] in the treatment of rheumatoid arthritis, see: Shaw et al. (2011); Schattenkirchner (2000). The title compound was

synthesized as an immunomodulating leflunomide analog; for another immunomodulating leflunomide analog, see: Huang et al. (2003).

Experimental top

A solution of 0.05 mol of 5-methylisoxazole-4-carboxylic acid chloride (7.3 g) in 20 ml of acetonitrile was added dropwise, while stirring, to 0.1 mol of 4-chloro-2-nitroaniline (17.2 g), dissolved in 150 ml of acetonitrile, at room temperature. After stirring for 40 more minutes, the precipitated 4-chloro-2-nitroaniline hydrochloride was filtered off and washed with 100 ml portions of acetonitrile, and the combined filtrates were concentrated under reduced pressure. 9.6 g (65% of theory) of yellow crytalline 5-methyl-N-(4-Chloro-2-nitrophenyl)isoxazole-4-carboxamide were thus obtained. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of toluene solution.

Refinement top

Carbon- and nitrogen-bound H atoms were placed in calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.96 (methyl), 0.97 (methylene) and N—H = 0.86 Å, Uiso(H) = 1.2 Ueq(C, N). The positions of methyl hydrogens were optimized rotationally with Uiso(H) = 1.5 Ueq(C).

Structure description top

Leflunomide is one of the most effective isoxazole-containing disease-modifying drugs for treating rheumatoid arthritis(Shaw et al., 2011; Schattenkirchner, 2000). Many leflunomide analogs have been synthesized and exhibit potent immunomodulating effect (Huang, et al., 2003). The title compound, 5-methyl-N-(4-chloro-2-nitrophenyl)isoxazole-4-carboxamide (I), was synthesized as a novel and potent immunomodulating leflunomide analog. We report herein its crystal structure. The molecular structure of the title compound is shown in Fig. 1. The nitro group is approximately coplanar with the benzene ring, as indicated by the torsion angle O1—N1—C5—C4 of 8.4 (3)°. The amide group is also coplanar with the benzene and isoxazole rings [torsion angles N2—C7—C8—C9 and C7—N2—C6—C1 are -8.9 (4) and -3.1 (4)°], respectively. The molecular conformation is stabilized by an intra-molecular N—H···O hydrogen bond (Table 1). In the crystal, infinite zigzag chain are formed via short inter-molecular Cl···O contacts of 3.089 (3) Å.

For applications of leflunomide [systematic name: 5-methyl-N-[4-(trifluoromethyl) phenyl]-isoxazole-4-carboxamide] in the treatment of rheumatoid arthritis, see: Shaw et al. (2011); Schattenkirchner (2000). The title compound was

synthesized as an immunomodulating leflunomide analog; for another immunomodulating leflunomide analog, see: Huang et al. (2003).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids.
N-(4-Chloro-2-nitrophenyl)-5-methylisoxazole-4-carboxamide top
Crystal data top
C11H8ClN3O4F(000) = 576
Mr = 281.65Dx = 1.583 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 5.3870 (11) Åθ = 9–13°
b = 23.537 (5) ŵ = 0.34 mm−1
c = 9.4600 (19) ÅT = 293 K
β = 99.86 (3)°Block, white
V = 1181.8 (4) Å30.30 × 0.20 × 0.10 mm
Z = 4
Data collection top
Enraf–Nonius CAD-4
diffractometer		1558 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.044
Graphite monochromatorθmax = 25.2°, θmin = 1.7°
ω/2θ scansh = 0→6
Absorption correction: ψ scan
(North et al., 1968)		k = −28→28
Tmin = 0.905, Tmax = 0.967l = −11→11
4645 measured reflections3 standard reflections every 200 reflections
2121 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.042H-atom parameters constrained
wR(F2) = 0.143 w = 1/[σ2(Fo2) + (0.090P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
2121 reflectionsΔρmax = 0.18 e Å−3
174 parametersΔρmin = −0.22 e Å−3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.010 (3)
Crystal data top
C11H8ClN3O4V = 1181.8 (4) Å3
Mr = 281.65Z = 4
Monoclinic, P21/cMo Kα radiation
a = 5.3870 (11) ŵ = 0.34 mm−1
b = 23.537 (5) ÅT = 293 K
c = 9.4600 (19) Å0.30 × 0.20 × 0.10 mm
β = 99.86 (3)°
Data collection top
Enraf–Nonius CAD-4
diffractometer		1558 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.044
Tmin = 0.905, Tmax = 0.9673 standard reflections every 200 reflections
4645 measured reflections intensity decay: 1%
2121 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.143H-atom parameters constrained
S = 1.02Δρmax = 0.18 e Å−3
2121 reflectionsΔρmin = −0.22 e Å−3
174 parameters
Special details top

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.

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 > σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl1.14810 (15)0.27507 (3)0.51209 (9)0.0712 (3)
N10.5249 (4)0.33771 (10)0.8313 (2)0.0534 (6)
C10.8613 (5)0.42551 (11)0.5906 (3)0.0476 (6)
H1A0.87680.46280.56060.057*
O10.5463 (5)0.28905 (9)0.8742 (3)0.0868 (8)
O20.3751 (4)0.37087 (9)0.8716 (2)0.0611 (5)
C20.9988 (5)0.38350 (11)0.5390 (3)0.0507 (6)
H2A1.10700.39270.47570.061*
N20.5564 (4)0.45566 (9)0.7398 (2)0.0469 (5)
H2B0.45590.44400.79510.056*
N30.0876 (5)0.56302 (12)0.9317 (3)0.0656 (7)
O30.6784 (4)0.53680 (8)0.6379 (2)0.0586 (5)
C30.9774 (5)0.32777 (11)0.5806 (3)0.0475 (6)
O40.1878 (4)0.61421 (9)0.8857 (2)0.0658 (6)
C40.8225 (5)0.31427 (11)0.6765 (3)0.0501 (6)
H4A0.80990.27680.70600.060*
C50.6850 (5)0.35645 (10)0.7294 (2)0.0434 (6)
C60.6978 (4)0.41348 (10)0.6875 (2)0.0406 (5)
C70.5541 (5)0.51330 (10)0.7158 (2)0.0433 (6)
C80.3842 (4)0.54381 (11)0.7965 (2)0.0444 (6)
C90.2056 (5)0.52340 (12)0.8774 (3)0.0555 (7)
H9A0.17630.48500.89010.067*
C100.3644 (5)0.60153 (11)0.8058 (3)0.0522 (7)
C110.4990 (7)0.65000 (12)0.7545 (4)0.0731 (9)
H11A0.41810.68480.77370.110*
H11B0.49580.64640.65320.110*
H11C0.67050.65030.80350.110*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl0.0730 (5)0.0583 (5)0.0884 (6)0.0099 (4)0.0308 (4)−0.0103 (4)
N10.0613 (14)0.0467 (13)0.0561 (12)−0.0111 (11)0.0211 (11)0.0031 (10)
C10.0504 (14)0.0448 (14)0.0502 (13)−0.0018 (12)0.0158 (11)0.0077 (11)
O10.121 (2)0.0491 (13)0.1062 (18)−0.0060 (12)0.0648 (16)0.0174 (11)
O20.0612 (12)0.0607 (12)0.0687 (12)−0.0006 (10)0.0320 (10)0.0094 (9)
C20.0515 (15)0.0515 (16)0.0530 (14)−0.0043 (12)0.0199 (12)0.0013 (11)
N20.0524 (12)0.0432 (12)0.0493 (11)−0.0006 (9)0.0210 (10)0.0049 (9)
N30.0568 (14)0.0717 (18)0.0722 (15)0.0055 (12)0.0221 (12)−0.0037 (12)
O30.0713 (13)0.0431 (11)0.0691 (11)−0.0025 (9)0.0335 (10)0.0048 (8)
C30.0449 (13)0.0467 (15)0.0520 (14)0.0003 (11)0.0112 (11)−0.0044 (11)
O40.0620 (12)0.0666 (14)0.0703 (12)0.0135 (10)0.0152 (10)−0.0107 (10)
C40.0541 (15)0.0379 (14)0.0587 (15)−0.0039 (11)0.0107 (13)0.0027 (11)
C50.0434 (13)0.0429 (14)0.0454 (13)−0.0068 (11)0.0123 (11)0.0015 (10)
C60.0430 (13)0.0411 (13)0.0377 (11)−0.0023 (10)0.0069 (10)0.0009 (9)
C70.0459 (13)0.0408 (13)0.0431 (13)−0.0014 (11)0.0069 (11)0.0017 (10)
C80.0433 (13)0.0464 (15)0.0428 (12)0.0017 (11)0.0053 (10)−0.0003 (10)
C90.0513 (15)0.0590 (18)0.0577 (15)−0.0006 (13)0.0140 (13)−0.0033 (13)
C100.0521 (15)0.0536 (16)0.0506 (14)0.0088 (13)0.0080 (12)−0.0030 (12)
C110.089 (2)0.0471 (17)0.086 (2)0.0019 (16)0.0222 (18)−0.0016 (15)
Geometric parameters (Å, º) top
Cl—C31.734 (3)O3—C71.210 (3)
N1—O11.214 (3)C3—C41.371 (4)
N1—O21.230 (3)O4—C101.346 (3)
N1—C51.467 (3)C4—C51.382 (3)
C1—C21.374 (4)C4—H4A0.9300
C1—C61.405 (3)C5—C61.405 (3)
C1—H1A0.9300C7—C81.475 (3)
C2—C31.380 (4)C8—C101.367 (4)
C2—H2A0.9300C8—C91.412 (4)
N2—C71.375 (3)C9—H9A0.9300
N2—C61.393 (3)C10—C111.477 (4)
N2—H2B0.8600C11—H11A0.9600
N3—C91.285 (3)C11—H11B0.9600
N3—O41.419 (3)C11—H11C0.9600
O1—N1—O2121.7 (2)C6—C5—N1122.4 (2)
O1—N1—C5118.0 (2)N2—C6—C1122.0 (2)
O2—N1—C5120.3 (2)N2—C6—C5121.6 (2)
C2—C1—C6121.5 (2)C1—C6—C5116.3 (2)
C2—C1—H1A119.2O3—C7—N2124.1 (2)
C6—C1—H1A119.2O3—C7—C8123.3 (2)
C1—C2—C3120.4 (2)N2—C7—C8112.5 (2)
C1—C2—H2A119.8C10—C8—C9103.6 (2)
C3—C2—H2A119.8C10—C8—C7125.4 (2)
C7—N2—C6129.4 (2)C9—C8—C7131.0 (2)
C7—N2—H2B115.3N3—C9—C8113.6 (3)
C6—N2—H2B115.3N3—C9—H9A123.2
C9—N3—O4104.7 (2)C8—C9—H9A123.2
C4—C3—C2119.9 (2)O4—C10—C8109.1 (2)
C4—C3—Cl120.2 (2)O4—C10—C11116.5 (3)
C2—C3—Cl119.8 (2)C8—C10—C11134.3 (3)
C10—O4—N3109.1 (2)C10—C11—H11A109.5
C3—C4—C5119.8 (2)C10—C11—H11B109.5
C3—C4—H4A120.1H11A—C11—H11B109.5
C5—C4—H4A120.1C10—C11—H11C109.5
C4—C5—C6121.9 (2)H11A—C11—H11C109.5
C4—C5—N1115.7 (2)H11B—C11—H11C109.5
C6—C1—C2—C30.7 (4)C4—C5—C6—C1−1.0 (3)
C1—C2—C3—C4−1.5 (4)N1—C5—C6—C1179.2 (2)
C1—C2—C3—Cl178.87 (19)C6—N2—C7—O32.0 (4)
C9—N3—O4—C10−0.4 (3)C6—N2—C7—C8−177.5 (2)
C2—C3—C4—C51.1 (4)O3—C7—C8—C10−7.0 (4)
Cl—C3—C4—C5−179.31 (19)N2—C7—C8—C10172.5 (2)
C3—C4—C5—C60.2 (4)O3—C7—C8—C9171.5 (2)
C3—C4—C5—N1180.0 (2)N2—C7—C8—C9−8.9 (4)
O1—N1—C5—C48.4 (3)O4—N3—C9—C80.4 (3)
O2—N1—C5—C4−171.8 (2)C10—C8—C9—N3−0.2 (3)
O1—N1—C5—C6−171.8 (2)C7—C8—C9—N3−179.0 (2)
O2—N1—C5—C67.9 (4)N3—O4—C10—C80.3 (3)
C7—N2—C6—C1−3.1 (4)N3—O4—C10—C11−177.0 (2)
C7—N2—C6—C5176.7 (2)C9—C8—C10—O4−0.1 (3)
C2—C1—C6—N2−179.6 (2)C7—C8—C10—O4178.8 (2)
C2—C1—C6—C50.6 (3)C9—C8—C10—C11176.5 (3)
C4—C5—C6—N2179.2 (2)C7—C8—C10—C11−4.6 (5)
N1—C5—C6—N2−0.6 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···O20.861.942.629 (3)136

Experimental details

Crystal data
Chemical formulaC11H8ClN3O4
Mr281.65
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)5.3870 (11), 23.537 (5), 9.4600 (19)
β (°) 99.86 (3)
V (Å3)1181.8 (4)
Z4
Radiation typeMo Kα
µ (mm−1)0.34
Crystal size (mm)0.30 × 0.20 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.905, 0.967
No. of measured, independent and
observed [I > 2σ(I)] reflections		4645, 2121, 1558
Rint0.044
(sin θ/λ)max (Å−1)0.599
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.143, 1.02
No. of reflections2121
No. of parameters174
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.18, −0.22

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···O20.861.942.629 (3)135.6
 

Acknowledgements

The work was supported by the Center of Testing and Analysis, Nanjing University.

References

First citationEnraf–Nonius (1994). CAD-4 EXPRESS. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
 First citationHarms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.  Google Scholar
 First citationHuang, W. H., Yang, C. L., LEE, A. R. & Chiu, H. F. (2003). Chem. Pharm. Bull. 51, 313–314.  CrossRef PubMed CAS Google Scholar
 First citationNorth, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.  CrossRef IUCr Journals Web of Science Google Scholar
 First citationSchattenkirchner, M. (2000). Immunopharmacology, 47, 291–298.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationShaw, J. J., Chen, B., Wooley, P., Palfey, B., Lee, A. R., Huang, W. H. & Zeng, D. (2011). Am. J. Biomed. Sci. 3, 218–227.  CrossRef CAS Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 12| December 2011| Page o3332
https://doi.org/10.1107/S1600536811047994
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