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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 65| Part 5| May 2009| Page o984
doi:10.1107/S1600536809012173

2-Methyl-1,10b-di­hydro-5H-pyrazolo[1,5-c][1,3]benzoxazin-5-one

Viktor Kettmanna* and Jan Světlíka

aFaculty of Pharmacy, Comenius University, Odbojarov 10, SK-83232 Bratislava, Slovakia
*Correspondence e-mail: kettmann@fpharm.uniba.sk

(Received 9 March 2009; accepted 1 April 2009; online 8 April 2009)

In the title compound, C11H10N2O2, a potential inhibitor of the cyclo­oxygenase-2 isoenzyme, the pyrazoline ring exists in a flat-envelope conformation while the puckering of the central oxazine ring is more severe. As a result, the mol­ecule as a whole is non-planar. The formal sp3 pyrazoline N atom is sp2 hybridized, with the lone-pair electrons delocalized through conjugation with the carbonyl group rather than the double bond of the pyrazoline ring.

Related literature

For cyclo­oxygenase-2 (COX-2), see: Jahng et al. (2004[Jahng, Y., Zhao, L. X., Moon, Y. S., Basnet, A., Kim, E., Chang, H. W., Ju, H. K., Jeong, T. C. & Lee, E. S. (2004). Bioorg. Med. Chem. Lett. pp. 2559-2563.]); Ramatunge et al. (2004[Ramatunge, R. R., Augustyniuk, M., Bandarage, U. P., Earl, R. A., Ellis, J. L., Garvey, D. S., Janero, D. R., Letts, L. G., Martino, A. M., Murty, M. G., Richardson, S. K., Schroeder, J. D., Shumway, M. J., Tam, S. W., Trocha, A. M. & Young, D. V. (2004). J. Med. Chem. 47, 2180-2189.]); Subbaramaiah et al. (2002[Subbaramaiah, K., Norton, L., Gerald, W. & Dannenberg, A. J. (2002). J. Biol. Chem. 277, 18649-18659.]). For bond parameters, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]); Burke-Laing & Laing (1976[Burke-Laing, M. & Laing, M. (1976). Acta Cryst. B32, 3216-3224.]). For background to the synthesis, see: Palomer et al. (2002[Palomer, A., Cabré, F., Pascual, J., Campos, J., Trujillo, M. A., Entrena, A., Gallo, M. A., Garcia, L., Mauleón, D. & Espinosa, A. (2002). J. Med. Chem. 45, 1402-1411.]); Světlík et al. (2005[Světlík, J., Pronayova, N. & Kubista, J. (2005). J. Heterocycl. Chem. 42, 1143-1147.]).

[Scheme 1]

Experimental

Crystal data

  • C11H10N2O2

  • Mr = 202.21

  • Orthorhombic, P 21 21 21

  • a = 7.240 (2) Å

  • b = 8.835 (2) Å

  • c = 15.755 (4) Å

  • V = 1007.8 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 296 K

  • 0.30 × 0.25 × 0.20 mm
Data collection

  • Siemens P4 diffractometer

  • Absorption correction: none

  • 2285 measured reflections

  • 1674 independent reflections

  • 1343 reflections with I > 2σ(I)

  • Rint = 0.021

  • 3 standard reflections every 97 reflections intensity decay: none
Refinement

  • R[F2 > 2σ(F2)] = 0.055

  • wR(F2) = 0.161

  • S = 0.96

  • 1674 reflections

  • 137 parameters

  • H-atom parameters constrained

  • Δρmax = 0.26 e Å−3

  • Δρmin = −0.22 e Å−3

Data collection: XSCANS (Siemens, 1991[Siemens (1991). XSCANS. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.]); cell refinement: XSCANS; data reduction: XSCANS; 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: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809012173/tk2391sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809012173/tk2391Isup2.hkl

checkCIF report


Comment top

Recently, as part of our on-going project aimed at developing new therapeutic agents, we focused our attention on 2-pyrazoline derivatives, which are known to possess cyclooxygenase-2 (COX-2) inhibitory activity (Jahng et al., 2004), a feature which is of importance in treatment of inflammation (Ramatunge et al., 2004) and cancer (Subbaramaiah et al., 2002). In an effort to develop more potent and selective COX-2 inhibitors, we prepared a series of 2- and 5-substituted derivatives containing the tricyclic system featured in the title compound, (I), which still incorporates the putative COX-2 pharmacophore (Palomer et al., 2002). Thus, the main aim of this work was to establish the spatial distribution of the pharmacophoric elements, viz. the hydrophobic groups and H-bond acceptors, which are responsible for binding of a compound to the COX-2 enzyme. To achieve this, we selected the title 2-methyl derivative, (I), for a single-crystal X-ray analysis.

The most interesting feature of (I), Fig. 1, is the spatial relationship between the pharmacophoric groups which is determined by the conformation of the (partially) saturated rings. Thus, the pyrazoline ring adopts a flat-envelope conformation with atom C10B as the flap; the deviation of the out-of-plane atom from the mean plane of the remaining four atoms is 0.334 (6) Å. The central six-membered ring is also non-planar and is puckered in such a manner that the four atoms O6, C6A, C10A and C10B are planar to within 0.004 (2) Å, while atoms N4 and C5 are displaced by 0.696 (5) and 0.590 (6) Å, respectively, to the same side of this plane. As a result of the relatively severe puckering of the central ring, the molecule as a whole is non-planar but consists of two approximately planar segments: O6,C6A,C7,C8,C9,C10,C10A,C10B [r.m.s. deviation 0.014 (3) Å] and C10B,C1,C2,C11,N3,N4,C5,O5,O6 [r.m.s. deviation 0.112 (3) Å], folded about the O6···C10B line [dihedral angle 31.3 (1)°].

The N3—N4 and C2—N3 bonds have pure single- and double-bond character, respectively (Burke-Laing & Laing, 1976). Even though the N4 atom is not involved in conjugation with the pyrazoline double bond, it is sp2 hybridized with its lone-pair electrons delocalized through conjugation with the adjacent carbonyl function as shown by the N4—C5 bond length (1.332 (4) Å), which is comparable to that typically found for amides (Allen et al., 1987).

Related literature top

For cyclooxygenase-2 (COX-2), see: Jahng et al. (2004); Ramatunge et al. (2004); Subbaramaiah et al. (2002). For bond parameters, see: Allen et al. (1987); Burke-Laing & Laing (1976). For background to the synthesis, see: Palomer et al. (2002); Světlík et al. (2005).

Experimental top

The synthesis of the title compound, (I), has been described (Světlík et al., 2005). In short, a solution of 4,5-dihydro-(2-hydroxyphenyl)-3-methyl-1H-pyrazole (0.35 g, 2 mmol) and N,N'-carbonyldiimidazole (0.36 g, 2.2 mmol) in benzene (15 ml) were refluxed for 200 mins. After removal of the solvent, the oily residue was dissolved in dichloromethane (25 ml), washed with 10% HCl, water and dried (MgSO4). The solution was then concentrated under reduced pressure to give (I) (90% yield; m.p. 433–434 K) as colourless crystals.

Refinement top

The H atoms were visible in difference maps and were subsequently treated as riding atoms with distances C—H = 0.93 Å (CHarom), 0.97 (CH2), 0.98 Å (CH) and 0.96 Å (CH3), and with Uiso(H) set to 1.2 (1.5 for the methyl H atoms) times Ueq(parent atom). In the absence of significant anomalous scattering effects, 370 Friedel pairs were averaged in the final refinement.

Computing details top

Data collection: XSCANS (Siemens, 1991); cell refinement: XSCANS (Siemens, 1991); data reduction: XSCANS (Siemens, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Displacement ellipsoid plot of (I) with the labelling scheme for the non-H atoms, which are drawn with displacement ellipsoids at the 35% probability level.
2-Methyl-1,10b-dihydro-5H-pyrazolo[1,5-c][1,3]benzoxazin-5-one top
Crystal data top
C11H10N2O2Dx = 1.333 Mg m−3
Mr = 202.21Melting point: 433 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 20 reflections
a = 7.240 (2) Åθ = 7–18°
b = 8.835 (2) ŵ = 0.09 mm−1
c = 15.755 (4) ÅT = 296 K
V = 1007.8 (4) Å3Prism, colourless
Z = 40.30 × 0.25 × 0.20 mm
F(000) = 424
Data collection top
Siemens P4
diffractometer		Rint = 0.021
Radiation source: fine-focus sealed tubeθmax = 30.0°, θmin = 2.6°
Graphite monochromatorh = −1→10
ω/2θ scansk = −1→12
2285 measured reflectionsl = −1→22
1674 independent reflections3 standard reflections every 97 reflections
1343 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.055Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.161H-atom parameters constrained
S = 0.96 w = 1/[σ2(Fo2) + (0.058P)2 + 0.7099P]
where P = (Fo2 + 2Fc2)/3
1674 reflections(Δ/σ)max = 0.003
137 parametersΔρmax = 0.26 e Å−3
0 restraintsΔρmin = −0.22 e Å−3
Crystal data top
C11H10N2O2V = 1007.8 (4) Å3
Mr = 202.21Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.240 (2) ŵ = 0.09 mm−1
b = 8.835 (2) ÅT = 296 K
c = 15.755 (4) Å0.30 × 0.25 × 0.20 mm
Data collection top
Siemens P4
diffractometer		Rint = 0.021
2285 measured reflections3 standard reflections every 97 reflections
1674 independent reflections intensity decay: none
1343 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0550 restraints
wR(F2) = 0.161H-atom parameters constrained
S = 0.96Δρmax = 0.26 e Å−3
1674 reflectionsΔρmin = −0.22 e Å−3
137 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

- 6.4736 (0.0083) x + 3.9501 (0.0194) y + 0.3894 (0.0333) z = 1.1812 (0.0071)

* 0.0059 (0.0012) C1 * -0.0108 (0.0022) C2 * 0.0108 (0.0022) N3 * -0.0060 (0.0012) N4 - 0.3338 (0.0055) C10B

Rms deviation of fitted atoms = 0.0087

7.0450 (0.0031) x - 0.1068 (0.0223) y + 3.6269 (0.0223) z = 1.0294 (0.0128)

Angle to previous plane (with approximate e.s.d.) = 29.57 (0.16)

* -0.0027 (0.0010) O6 * 0.0053 (0.0019) C6A * -0.0050 (0.0018) C10A * 0.0024 (0.0009) C10B -0.6963 (0.0054) N4 - 0.5900 (0.0063) C5

Rms deviation of fitted atoms = 0.0041

7.0642 (0.0025) x - 0.1723 (0.0086) y + 3.4371 (0.0150) z = 0.9846 (0.0059)

Angle to previous plane (with approximate e.s.d.) = 0.82 (0.08)

* -0.0143 (0.0023) O6 * -0.0087 (0.0029) C6A * 0.0109 (0.0030) C7 * 0.0160 (0.0032) C8 * -0.0063 (0.0031) C9 * -0.0177 (0.0029) C10 * -0.0034 (0.0027) C10A * 0.0234 (0.0023) C10B

Rms deviation of fitted atoms = 0.0140

- 6.2356 (0.0052) x + 4.4868 (0.0103) y - 0.2799 (0.0136) z = 1.4163 (0.0043)

Angle to previous plane (with approximate e.s.d.) = 31.34 (0.08)

* -0.2463 (0.0027) C10B * 0.1374 (0.0029) C1 * 0.0194 (0.0039) C2 * -0.0476 (0.0032) N3 * -0.0351 (0.0028) N4 * 0.0138 (0.0033) C5 * 0.1614 (0.0027) O6 * 0.0426 (0.0034) C11 * -0.0456 (0.0025) O5

Rms deviation of fitted atoms = 0.1123

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
C10.1064 (5)0.4867 (4)−0.11974 (19)0.0540 (8)
H1A0.01970.5671−0.13280.065*
H1B0.21070.4926−0.15820.065*
C20.0157 (5)0.3341 (4)−0.1229 (2)0.0600 (9)
N3−0.0199 (4)0.2741 (3)−0.05137 (18)0.0581 (7)
N40.0479 (4)0.3750 (3)0.00991 (16)0.0484 (6)
C50.0201 (5)0.3524 (4)0.0925 (2)0.0523 (8)
O5−0.0494 (5)0.2447 (3)0.12627 (15)0.0761 (9)
O60.0794 (4)0.4709 (3)0.14279 (14)0.0583 (7)
C6A0.1009 (4)0.6157 (3)0.1075 (2)0.0475 (7)
C70.0800 (5)0.7370 (4)0.1622 (2)0.0594 (9)
H70.05320.72190.21930.071*
C80.1000 (6)0.8811 (4)0.1297 (3)0.0675 (11)
H80.08730.96430.16540.081*
C90.1389 (5)0.9035 (4)0.0445 (3)0.0669 (11)
H90.15071.00110.02300.080*
C100.1601 (5)0.7788 (4)−0.0086 (3)0.0569 (8)
H100.18580.7931−0.06590.068*
C10A0.1430 (4)0.6339 (3)0.0233 (2)0.0431 (6)
C10B0.1680 (5)0.4926 (3)−0.02737 (18)0.0429 (6)
H10B0.29710.4598−0.02350.051*
C11−0.0392 (8)0.2580 (7)−0.2042 (3)0.0990 (19)
H11A−0.09120.1605−0.19180.149*
H11B0.06770.2458−0.23960.149*
H11C−0.12900.3190−0.23310.149*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.060 (2)0.0602 (18)0.0414 (14)−0.0014 (17)0.0052 (15)−0.0004 (14)
C20.062 (2)0.071 (2)0.0464 (16)−0.011 (2)0.0099 (16)−0.0100 (16)
N30.0687 (18)0.0535 (14)0.0521 (14)−0.0145 (16)0.0099 (14)−0.0113 (13)
N40.0602 (15)0.0425 (12)0.0424 (12)−0.0082 (13)0.0002 (12)0.0010 (10)
C50.069 (2)0.0450 (15)0.0434 (14)−0.0054 (17)−0.0015 (16)0.0022 (13)
O50.116 (2)0.0590 (14)0.0528 (13)−0.0199 (17)0.0073 (15)0.0105 (12)
O60.0811 (18)0.0495 (12)0.0442 (11)−0.0036 (13)−0.0074 (13)0.0021 (9)
C6A0.0454 (15)0.0438 (15)0.0532 (17)−0.0029 (14)−0.0089 (14)−0.0026 (13)
C70.058 (2)0.0586 (19)0.0614 (19)0.0009 (18)−0.0116 (17)−0.0163 (17)
C80.061 (2)0.0489 (18)0.092 (3)0.0013 (18)−0.013 (2)−0.023 (2)
C90.055 (2)0.0353 (14)0.110 (3)−0.0010 (15)−0.005 (2)−0.0001 (18)
C100.0453 (16)0.0542 (19)0.071 (2)−0.0042 (15)−0.0013 (17)0.0076 (18)
C10A0.0356 (13)0.0404 (13)0.0533 (16)0.0044 (12)−0.0012 (13)−0.0006 (12)
C10B0.0420 (14)0.0383 (13)0.0484 (15)−0.0037 (12)0.0046 (13)0.0062 (12)
C110.106 (4)0.137 (4)0.054 (2)−0.050 (4)0.016 (2)−0.038 (3)
Geometric parameters (Å, º) top
C1—C21.501 (5)C7—C81.380 (5)
C1—C10B1.523 (4)C7—H70.9300
C1—H1A0.9700C8—C91.385 (6)
C1—H1B0.9700C8—H80.9300
C2—N31.272 (4)C9—C101.393 (5)
C2—C111.499 (5)C9—H90.9300
N3—N41.403 (4)C10—C10A1.381 (4)
N4—C51.332 (4)C10—H100.9300
N4—C10B1.477 (4)C10A—C10B1.493 (4)
C5—O51.200 (4)C10B—H10B0.9800
C5—O61.381 (4)C11—H11A0.9600
O6—C6A1.404 (4)C11—H11B0.9600
C6A—C10A1.371 (4)C11—H11C0.9600
C6A—C71.383 (4)
C2—C1—C10B101.0 (3)C7—C8—H8119.6
C2—C1—H1A111.6C9—C8—H8119.6
C10B—C1—H1A111.6C8—C9—C10119.5 (3)
C2—C1—H1B111.6C8—C9—H9120.3
C10B—C1—H1B111.6C10—C9—H9120.3
H1A—C1—H1B109.4C10A—C10—C9120.3 (3)
N3—C2—C1115.7 (3)C10A—C10—H10119.8
N3—C2—C11121.1 (4)C9—C10—H10119.8
C1—C2—C11123.2 (3)C6A—C10A—C10118.8 (3)
C2—N3—N4105.9 (3)C6A—C10A—C10B116.5 (3)
C5—N4—N3121.6 (3)C10—C10A—C10B124.7 (3)
C5—N4—C10B125.7 (3)N4—C10B—C10A107.7 (2)
N3—N4—C10B112.3 (2)N4—C10B—C1100.6 (3)
O5—C5—N4127.9 (3)C10A—C10B—C1120.3 (3)
O5—C5—O6118.5 (3)N4—C10B—H10B109.2
N4—C5—O6113.6 (3)C10A—C10B—H10B109.2
C5—O6—C6A119.9 (2)C1—C10B—H10B109.2
C10A—C6A—C7122.4 (3)C2—C11—H11A109.5
C10A—C6A—O6121.0 (3)C2—C11—H11B109.5
C7—C6A—O6116.6 (3)H11A—C11—H11B109.5
C8—C7—C6A118.2 (4)C2—C11—H11C109.5
C8—C7—H7120.9H11A—C11—H11C109.5
C6A—C7—H7120.9H11B—C11—H11C109.5
C7—C8—C9120.8 (3)
C10B—C1—C2—N314.6 (4)C8—C9—C10—C10A−0.2 (6)
C10B—C1—C2—C11−168.2 (4)C7—C6A—C10A—C10−1.9 (5)
C1—C2—N3—N4−2.2 (4)O6—C6A—C10A—C10179.1 (3)
C11—C2—N3—N4−179.4 (4)C7—C6A—C10A—C10B177.9 (3)
C2—N3—N4—C5174.6 (4)O6—C6A—C10A—C10B−1.2 (4)
C2—N3—N4—C10B−12.4 (4)C9—C10—C10A—C6A1.5 (5)
N3—N4—C5—O55.9 (7)C9—C10—C10A—C10B−178.3 (3)
C10B—N4—C5—O5−166.1 (4)C5—N4—C10B—C10A−40.0 (4)
N3—N4—C5—O6−173.5 (3)N3—N4—C10B—C10A147.3 (3)
C10B—N4—C5—O614.4 (5)C5—N4—C10B—C1−166.7 (3)
O5—C5—O6—C6A−158.0 (4)N3—N4—C10B—C120.6 (3)
N4—C5—O6—C6A21.5 (5)C6A—C10A—C10B—N430.5 (4)
C5—O6—C6A—C10A−28.5 (5)C10—C10A—C10B—N4−149.8 (3)
C5—O6—C6A—C7152.4 (3)C6A—C10A—C10B—C1144.7 (3)
C10A—C6A—C7—C81.0 (5)C10—C10A—C10B—C1−35.6 (5)
O6—C6A—C7—C8−180.0 (3)C2—C1—C10B—N4−19.1 (3)
C6A—C7—C8—C90.4 (6)C2—C1—C10B—C10A−137.0 (3)
C7—C8—C9—C10−0.8 (6)

Experimental details

Crystal data
Chemical formulaC11H10N2O2
Mr202.21
Crystal system, space groupOrthorhombic, P212121
Temperature (K)296
a, b, c (Å)7.240 (2), 8.835 (2), 15.755 (4)
V (Å3)1007.8 (4)
Z4
Radiation typeMo Kα
µ (mm−1)0.09
Crystal size (mm)0.30 × 0.25 × 0.20
Data collection
DiffractometerSiemens P4
diffractometer
Absorption correction–
No. of measured, independent and
observed [I > 2σ(I)] reflections		2285, 1674, 1343
Rint0.021
(sin θ/λ)max (Å−1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.161, 0.96
No. of reflections1674
No. of parameters137
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.26, −0.22

Computer programs: XSCANS (Siemens, 1991), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).

 

Acknowledgements

This work was supported by the Grant Agency of the Slovak Republic, project No. 1/4298/07.

References

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ISSN: 2056-9890
Volume 65| Part 5| May 2009| Page o984
doi:10.1107/S1600536809012173
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