organic compounds
4-[(5R*,10bR*)-2-Methyl-1,10b-dihydropyrazolo[1,5-c][1,3]benzoxazin-5-yl]benzoic acid
aFaculty of Pharmacy, Comenius University, Odbojarov 10, SK-83232 Bratislava, Slovakia
*Correspondence e-mail: kettmann@fpharm.uniba.sk
In the title compound, C18H16N2O3, a potential inhibitor of the cyclooxygenase-2 the pyrazoline ring exists in a flattened with one C atom deviating by 0.463 Å from the mean plane of the remaining four atoms. The puckering of the central oxazine ring is more severe, with one N atom and one C atom displaced by 0.235 (6) and 0.370 (2) Å, respectively, on opposite sides of the mean plane defined by the other four atoms; the conformation is that of a half-chair. As a result, the molecule as a whole is not planar. The carboxyl group is involved in an intermolecular O—H⋯N hydrogen bond, which links the molecules into centrosymmetric dimers.
Related literature
For related literature, see: Palomer et al. (2002); Subbaramaiah et al. (2002); Světlík et al. (2005).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: XSCANS (Siemens, 1991); cell XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536808003607/bi2280sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808003607/bi2280Isup2.hkl
Synthesis of the title compound has been described previously (Světlík et al., 2005). In short, a solution of 4-carboxybenzaldehyde (0.30 g, 2 mmol) and pyrazoline (0.35 g, 2 mmol) in ethyl acetate (14 ml) and methanol (1 ml) was left to react at room temperature for 1 h. The resulting precipitate was filtered off and crystallized from ethanol to obtain (1a) (70% yield; m.p. 474–480 K) as colourless crystals. Crystals suitable for the X-ray analysis were obtained by slow crystallization from acetone.
H atoms were visible in difference maps, but were placed geometrically and subsequently treated as riding atoms with distances C—H = 0.93 Å (CHarom), 0.97 (CH2) or 0.98 Å (CH) and 0.96 Å (CH3) and O—H = 0.82 Å (COOH); Uiso of the H atoms were set to 1.2 (1.5 for the methyl and carboxy H atoms) times Ueq of the parent atom.
Data collection: XSCANS (Siemens, 1991); cell
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, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. The cis title compound (1a) and its trans isomer (1 b). | |
Fig. 2. Molecular structure with displacement ellipsoids drawn at 35% probability for non-H atoms. |
C18H16N2O3 | Z = 2 |
Mr = 308.33 | F(000) = 324 |
Triclinic, P1 | Dx = 1.365 Mg m−3 |
Hall symbol: -P 1 | Melting point: 477 K |
a = 6.638 (2) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 10.997 (3) Å | Cell parameters from 20 reflections |
c = 11.141 (3) Å | θ = 7–18° |
α = 70.78 (2)° | µ = 0.09 mm−1 |
β = 80.85 (3)° | T = 296 K |
γ = 79.15 (2)° | Prism, colourless |
V = 750.1 (4) Å3 | 0.30 × 0.20 × 0.15 mm |
Siemens P4 diffractometer | Rint = 0.019 |
Radiation source: fine-focus sealed tube | θmax = 30.0°, θmin = 2.0° |
Graphite monochromator | h = −1→9 |
ω/2θ scans | k = −14→14 |
5341 measured reflections | l = −15→15 |
4312 independent reflections | 3 standard reflections every 97 reflections |
3216 reflections with I > 2σ(I) | intensity decay: none |
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)] = 0.051 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.152 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0853P)2 + 0.0987P] where P = (Fo2 + 2Fc2)/3 |
4312 reflections | (Δ/σ)max = 0.001 |
210 parameters | Δρmax = 0.29 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C18H16N2O3 | γ = 79.15 (2)° |
Mr = 308.33 | V = 750.1 (4) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.638 (2) Å | Mo Kα radiation |
b = 10.997 (3) Å | µ = 0.09 mm−1 |
c = 11.141 (3) Å | T = 296 K |
α = 70.78 (2)° | 0.30 × 0.20 × 0.15 mm |
β = 80.85 (3)° |
Siemens P4 diffractometer | Rint = 0.019 |
5341 measured reflections | 3 standard reflections every 97 reflections |
4312 independent reflections | intensity decay: none |
3216 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.051 | 0 restraints |
wR(F2) = 0.152 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.29 e Å−3 |
4312 reflections | Δρmin = −0.22 e Å−3 |
210 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.3065 (2) | 0.63515 (13) | 0.03856 (13) | 0.0364 (3) | |
H1A | 0.3369 | 0.6320 | −0.0485 | 0.044* | |
H1B | 0.4338 | 0.6149 | 0.0780 | 0.044* | |
C2 | 0.1553 (2) | 0.54630 (12) | 0.11427 (12) | 0.0324 (3) | |
N3 | 0.01255 (17) | 0.59887 (10) | 0.18002 (10) | 0.0314 (2) | |
N4 | 0.05040 (17) | 0.72620 (10) | 0.16410 (10) | 0.0304 (2) | |
C5 | −0.1328 (2) | 0.81721 (13) | 0.17228 (12) | 0.0342 (3) | |
H5 | −0.0911 | 0.8976 | 0.1736 | 0.041* | |
O6 | −0.25382 (16) | 0.84950 (11) | 0.06661 (9) | 0.0440 (3) | |
C7 | −0.1451 (2) | 0.87381 (13) | −0.05137 (12) | 0.0371 (3) | |
C8 | −0.2589 (3) | 0.93655 (15) | −0.15442 (14) | 0.0479 (4) | |
H8 | −0.3999 | 0.9630 | −0.1409 | 0.057* | |
C9 | −0.1623 (3) | 0.95933 (18) | −0.27641 (16) | 0.0586 (5) | |
H9 | −0.2381 | 1.0010 | −0.3458 | 0.070* | |
C10 | 0.0466 (3) | 0.92058 (17) | −0.29635 (15) | 0.0560 (5) | |
H10 | 0.1116 | 0.9354 | −0.3792 | 0.067* | |
C11 | 0.1589 (3) | 0.86000 (14) | −0.19372 (13) | 0.0449 (4) | |
H11 | 0.3003 | 0.8352 | −0.2079 | 0.054* | |
C12 | 0.0646 (2) | 0.83525 (12) | −0.06896 (12) | 0.0347 (3) | |
C13 | 0.1871 (2) | 0.76641 (13) | 0.04385 (12) | 0.0330 (3) | |
H13 | 0.2808 | 0.8222 | 0.0510 | 0.040* | |
C14 | 0.1724 (2) | 0.40903 (14) | 0.11858 (15) | 0.0418 (3) | |
H14A | 0.2925 | 0.3598 | 0.1589 | 0.063* | |
H14B | 0.1840 | 0.4044 | 0.0332 | 0.063* | |
H14C | 0.0517 | 0.3737 | 0.1665 | 0.063* | |
C15 | −0.2727 (2) | 0.76809 (12) | 0.29245 (12) | 0.0329 (3) | |
C16 | −0.2086 (2) | 0.75161 (17) | 0.40981 (14) | 0.0448 (4) | |
H16 | −0.0830 | 0.7752 | 0.4137 | 0.054* | |
C17 | −0.3307 (3) | 0.70033 (17) | 0.52093 (14) | 0.0462 (4) | |
H17 | −0.2865 | 0.6890 | 0.5995 | 0.055* | |
C18 | −0.5184 (2) | 0.66557 (13) | 0.51636 (12) | 0.0342 (3) | |
C19 | −0.5837 (2) | 0.68431 (14) | 0.39930 (13) | 0.0374 (3) | |
H19 | −0.7103 | 0.6621 | 0.3952 | 0.045* | |
C20 | −0.4614 (2) | 0.73595 (14) | 0.28820 (13) | 0.0381 (3) | |
H20 | −0.5070 | 0.7492 | 0.2096 | 0.046* | |
C21 | −0.6403 (2) | 0.60087 (13) | 0.63696 (13) | 0.0361 (3) | |
O7 | −0.5895 (2) | 0.58142 (13) | 0.74163 (10) | 0.0520 (3) | |
O8 | −0.80628 (16) | 0.56450 (11) | 0.61698 (10) | 0.0454 (3) | |
H8A | −0.8571 | 0.5179 | 0.6845 | 0.068* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0382 (7) | 0.0364 (7) | 0.0318 (6) | −0.0088 (5) | 0.0038 (5) | −0.0084 (5) |
C2 | 0.0362 (6) | 0.0317 (6) | 0.0286 (6) | −0.0074 (5) | −0.0017 (5) | −0.0077 (5) |
N3 | 0.0364 (6) | 0.0285 (5) | 0.0281 (5) | −0.0088 (4) | −0.0002 (4) | −0.0065 (4) |
N4 | 0.0362 (5) | 0.0290 (5) | 0.0256 (5) | −0.0104 (4) | 0.0017 (4) | −0.0072 (4) |
C5 | 0.0423 (7) | 0.0310 (6) | 0.0282 (6) | −0.0086 (5) | 0.0016 (5) | −0.0082 (5) |
O6 | 0.0434 (5) | 0.0498 (6) | 0.0273 (5) | −0.0018 (5) | −0.0005 (4) | −0.0009 (4) |
C7 | 0.0514 (8) | 0.0290 (6) | 0.0273 (6) | −0.0098 (6) | −0.0004 (5) | −0.0034 (5) |
C8 | 0.0585 (9) | 0.0417 (8) | 0.0359 (7) | −0.0042 (7) | −0.0097 (7) | −0.0015 (6) |
C9 | 0.0890 (14) | 0.0478 (9) | 0.0316 (7) | −0.0059 (9) | −0.0143 (8) | −0.0009 (6) |
C10 | 0.0856 (13) | 0.0474 (9) | 0.0279 (7) | −0.0115 (9) | 0.0037 (8) | −0.0058 (6) |
C11 | 0.0624 (9) | 0.0362 (7) | 0.0313 (7) | −0.0126 (7) | 0.0087 (6) | −0.0072 (5) |
C12 | 0.0507 (8) | 0.0253 (6) | 0.0270 (6) | −0.0126 (5) | 0.0018 (5) | −0.0055 (4) |
C13 | 0.0368 (6) | 0.0331 (6) | 0.0288 (6) | −0.0134 (5) | 0.0036 (5) | −0.0079 (5) |
C14 | 0.0464 (8) | 0.0351 (7) | 0.0449 (8) | −0.0074 (6) | −0.0004 (6) | −0.0149 (6) |
C15 | 0.0403 (7) | 0.0287 (6) | 0.0276 (6) | −0.0059 (5) | 0.0024 (5) | −0.0081 (5) |
C16 | 0.0447 (8) | 0.0600 (9) | 0.0340 (7) | −0.0227 (7) | 0.0018 (6) | −0.0147 (6) |
C17 | 0.0524 (9) | 0.0628 (10) | 0.0270 (6) | −0.0203 (7) | −0.0002 (6) | −0.0139 (6) |
C18 | 0.0396 (7) | 0.0322 (6) | 0.0289 (6) | −0.0055 (5) | 0.0031 (5) | −0.0098 (5) |
C19 | 0.0359 (7) | 0.0410 (7) | 0.0329 (6) | −0.0087 (5) | −0.0014 (5) | −0.0076 (5) |
C20 | 0.0426 (7) | 0.0417 (7) | 0.0277 (6) | −0.0085 (6) | −0.0042 (5) | −0.0063 (5) |
C21 | 0.0405 (7) | 0.0337 (6) | 0.0311 (6) | −0.0055 (5) | 0.0038 (5) | −0.0097 (5) |
O7 | 0.0637 (7) | 0.0646 (7) | 0.0285 (5) | −0.0204 (6) | 0.0024 (5) | −0.0126 (5) |
O8 | 0.0457 (6) | 0.0506 (6) | 0.0336 (5) | −0.0165 (5) | 0.0032 (4) | −0.0029 (4) |
C1—C2 | 1.4934 (19) | C11—C12 | 1.3915 (19) |
C1—C13 | 1.5249 (19) | C11—H11 | 0.930 |
C1—H1A | 0.970 | C12—C13 | 1.5101 (19) |
C1—H1B | 0.970 | C13—H13 | 0.980 |
C2—N3 | 1.2730 (17) | C14—H14A | 0.960 |
C2—C14 | 1.4776 (19) | C14—H14B | 0.960 |
N3—N4 | 1.4178 (15) | C14—H14C | 0.960 |
N4—C5 | 1.4335 (18) | C15—C20 | 1.376 (2) |
N4—C13 | 1.4793 (17) | C15—C16 | 1.3839 (19) |
C5—O6 | 1.4409 (17) | C16—C17 | 1.379 (2) |
C5—C15 | 1.5047 (18) | C16—H16 | 0.930 |
C5—H5 | 0.980 | C17—C18 | 1.384 (2) |
O6—C7 | 1.3637 (17) | C17—H17 | 0.930 |
C7—C12 | 1.379 (2) | C18—C19 | 1.3783 (19) |
C7—C8 | 1.387 (2) | C18—C21 | 1.4856 (19) |
C8—C9 | 1.371 (2) | C19—C20 | 1.380 (2) |
C8—H8 | 0.930 | C19—H19 | 0.930 |
C9—C10 | 1.377 (3) | C20—H20 | 0.930 |
C9—H9 | 0.930 | C21—O7 | 1.2053 (17) |
C10—C11 | 1.375 (2) | C21—O8 | 1.3140 (18) |
C10—H10 | 0.930 | O8—H8A | 0.820 |
C2—C1—C13 | 100.79 (11) | C7—C12—C13 | 120.90 (12) |
C2—C1—H1A | 111.6 | C11—C12—C13 | 121.16 (14) |
C13—C1—H1A | 111.6 | N4—C13—C12 | 111.46 (11) |
C2—C1—H1B | 111.6 | N4—C13—C1 | 100.98 (10) |
C13—C1—H1B | 111.6 | C12—C13—C1 | 112.93 (11) |
H1A—C1—H1B | 109.4 | N4—C13—H13 | 110.4 |
N3—C2—C14 | 122.55 (13) | C12—C13—H13 | 110.4 |
N3—C2—C1 | 113.23 (12) | C1—C13—H13 | 110.4 |
C14—C2—C1 | 124.16 (12) | C2—C14—H14A | 109.5 |
C2—N3—N4 | 108.71 (11) | C2—C14—H14B | 109.5 |
N3—N4—C5 | 114.05 (10) | H14A—C14—H14B | 109.5 |
N3—N4—C13 | 107.26 (9) | C2—C14—H14C | 109.5 |
C5—N4—C13 | 114.20 (10) | H14A—C14—H14C | 109.5 |
N4—C5—O6 | 113.73 (11) | H14B—C14—H14C | 109.5 |
N4—C5—C15 | 112.11 (11) | C20—C15—C16 | 119.21 (13) |
O6—C5—C15 | 106.99 (11) | C20—C15—C5 | 121.22 (12) |
N4—C5—H5 | 107.9 | C16—C15—C5 | 119.55 (13) |
O6—C5—H5 | 107.9 | C17—C16—C15 | 120.12 (14) |
C15—C5—H5 | 107.9 | C17—C16—H16 | 119.9 |
C7—O6—C5 | 115.49 (11) | C15—C16—H16 | 119.9 |
O6—C7—C12 | 122.64 (12) | C16—C17—C18 | 120.50 (13) |
O6—C7—C8 | 116.04 (14) | C16—C17—H17 | 119.8 |
C12—C7—C8 | 121.29 (14) | C18—C17—H17 | 119.8 |
C9—C8—C7 | 119.60 (17) | C19—C18—C17 | 119.28 (13) |
C9—C8—H8 | 120.2 | C19—C18—C21 | 120.86 (13) |
C7—C8—H8 | 120.2 | C17—C18—C21 | 119.74 (13) |
C8—C9—C10 | 120.15 (16) | C18—C19—C20 | 120.10 (13) |
C8—C9—H9 | 119.9 | C18—C19—H19 | 119.9 |
C10—C9—H9 | 119.9 | C20—C19—H19 | 119.9 |
C11—C10—C9 | 119.92 (15) | C15—C20—C19 | 120.77 (13) |
C11—C10—H10 | 120.0 | C15—C20—H20 | 119.6 |
C9—C10—H10 | 120.0 | C19—C20—H20 | 119.6 |
C10—C11—C12 | 121.10 (16) | O7—C21—O8 | 123.78 (13) |
C10—C11—H11 | 119.4 | O7—C21—C18 | 123.50 (14) |
C12—C11—H11 | 119.4 | O8—C21—C18 | 112.71 (12) |
C7—C12—C11 | 117.93 (14) | C21—O8—H8A | 109.5 |
C13—C1—C2—N3 | −15.79 (15) | N3—N4—C13—C1 | −29.67 (12) |
C13—C1—C2—C14 | 166.98 (12) | C5—N4—C13—C1 | −157.08 (11) |
C14—C2—N3—N4 | 174.46 (11) | C7—C12—C13—N4 | 11.07 (17) |
C1—C2—N3—N4 | −2.82 (15) | C11—C12—C13—N4 | −167.94 (12) |
C2—N3—N4—C5 | 148.89 (11) | C7—C12—C13—C1 | 123.94 (13) |
C2—N3—N4—C13 | 21.40 (13) | C11—C12—C13—C1 | −55.08 (17) |
N3—N4—C5—O6 | −68.94 (13) | C2—C1—C13—N4 | 26.12 (12) |
C13—N4—C5—O6 | 54.89 (15) | C2—C1—C13—C12 | −93.01 (13) |
N3—N4—C5—C15 | 52.60 (14) | N4—C5—C15—C20 | −112.18 (15) |
C13—N4—C5—C15 | 176.43 (10) | O6—C5—C15—C20 | 13.15 (17) |
N4—C5—O6—C7 | −44.40 (16) | N4—C5—C15—C16 | 66.12 (17) |
C15—C5—O6—C7 | −168.75 (11) | O6—C5—C15—C16 | −168.55 (12) |
C5—O6—C7—C12 | 17.97 (19) | C20—C15—C16—C17 | 1.7 (2) |
C5—O6—C7—C8 | −164.03 (12) | C5—C15—C16—C17 | −176.64 (14) |
O6—C7—C8—C9 | −177.12 (14) | C15—C16—C17—C18 | −0.4 (3) |
C12—C7—C8—C9 | 0.9 (2) | C16—C17—C18—C19 | −0.8 (2) |
C7—C8—C9—C10 | −0.3 (3) | C16—C17—C18—C21 | 175.18 (15) |
C8—C9—C10—C11 | −0.6 (3) | C17—C18—C19—C20 | 0.7 (2) |
C9—C10—C11—C12 | 0.9 (3) | C21—C18—C19—C20 | −175.28 (13) |
O6—C7—C12—C11 | 177.24 (13) | C16—C15—C20—C19 | −1.9 (2) |
C8—C7—C12—C11 | −0.7 (2) | C5—C15—C20—C19 | 176.45 (13) |
O6—C7—C12—C13 | −1.8 (2) | C18—C19—C20—C15 | 0.7 (2) |
C8—C7—C12—C13 | −179.70 (13) | C19—C18—C21—O7 | 179.54 (14) |
C10—C11—C12—C7 | −0.2 (2) | C17—C18—C21—O7 | 3.6 (2) |
C10—C11—C12—C13 | 178.82 (14) | C19—C18—C21—O8 | 1.05 (19) |
N3—N4—C13—C12 | 90.51 (12) | C17—C18—C21—O8 | −174.89 (13) |
C5—N4—C13—C12 | −36.89 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8A···N3i | 0.82 | 1.93 | 2.7356 (17) | 168 |
Symmetry code: (i) −x−1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C18H16N2O3 |
Mr | 308.33 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 6.638 (2), 10.997 (3), 11.141 (3) |
α, β, γ (°) | 70.78 (2), 80.85 (3), 79.15 (2) |
V (Å3) | 750.1 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.30 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5341, 4312, 3216 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.051, 0.152, 1.01 |
No. of reflections | 4312 |
No. of parameters | 210 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.29, −0.22 |
Computer programs: XSCANS (Siemens, 1991), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8A···N3i | 0.82 | 1.93 | 2.7356 (17) | 167.7 |
Symmetry code: (i) −x−1, −y+1, −z+1. |
Acknowledgements
This work was supported by the Grant Agency of the Slovak Republic, project Nos. 1/4298/07 and 1/4299/07.
References
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Recently, based on a pharmacophoric model of the cyclooxygenase-2 (COX-2) inhibitors (Palomer et al., 2002) as novel anticancer drugs (Subbaramaiah et al., 2002), we designed and prepared a series of 2- and 5-substituted derivatives containing the tricyclic system shown in Fig. 1. In order to recognize enzyme binding requirements for this fused heterocycle, we selected the 2-methyl-5-carboxyphenyl derivative, for single-crystal X-ray analysis. The compound was obtained as a 1:1 mixture of the cis (1a) and trans (1 b) diastereomers and we report here the structure of the cis isomer.
The molecular structure and atom-numbering scheme is shown in Fig. 2. Bond distances and angles are close to those generally expected. The atom O6 is essentially sp2-hybridized and involved in conjugation with the benzo ring as indicated by the valence angle at this atom and a non-equivalency of the O6—C5 and O6—C7 bonds.
The most interesting feature of the structure—the spatial relationship between the pharmacophoric elements (hydrophobic groups and H-bond donors/acceptors)—is given by conformation of the (partially) saturated rings. Thus, the pyrazoline ring adopts a flat-envelope conformation with atom C13 (at the flap) deviating by 0.463 Å from the mean plane of the remaining atoms. The central oxazine ring is also non-planar and is puckered in such a manner that the four atoms O6, C7, C12 and C13 are planar to within 0.006 (2) Å, while atoms N4 and C5 are displaced by 0.235 (6) and 0.370 (2) Å, respectively, on opposite sides of the 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, C5/O6/C7–C13 and C13/C1/C2/N3/N4/C5, folded about the C5···C13 line [dihedral angle 71.7 (1)°]. The carboxyphenyl substituent is rotated by 39.8 (1)° from the mean plane of the oxazine ring.
The crystal packing is dominated by a hydrogen bond between centrosymmetrically related molecules (Table 1) which result in formation of hydrogen-bonded dimers.