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Terbogrel, (E)-6-[4-(3-tert-butyl-2-cyano­guanidino)­phenyl]-6-(3-pyridyl)­hex-5-enoic acid, C23H27N5O2, a mixed thromboxane A2 receptor antagonist and thromboxane A2 synthase inhibitor, shows a hairpin-like conformation stabilized by an intramolecular hydrogen bond. A structural feature characteristic of the thromboxane A2 synthase inhibitor mode is observed: a distance of 8.4257 (19) Å between the pyridine N atom and the carboxyl group.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100009872/gs1099sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100009872/gs1099Isup2.hkl
Contains datablock I

CCDC reference: 152630

Comment top

Terbogrel, (I), is a combined thromboxane A2 receptor antagonist (TRA) and thromboxane A2 synthase inhibitor (TxSI) (Soyka et al., 1999). In order to understand this dual mode of action, the structural properties of the compound have been studied and the results are presented here. \sch

A folded hairpin-like conformer is observed (Fig. 1), confirming the assumption of Andersen et al. (1976) that TXA2 receptor binding requires a prostaglandin conformation, with a U-shaped or approximately parallel arrangement of the α and ω side chains (the so-called hairpin conformation hypothesis). Such a conformation was also observed in S-145, a potent TRA, by Ezumi et al. (1990).

The crystal packing of (I) was then analysed and mainly intra- and intermolecular hydrogen bonds observed (Table 1). The hairpin-like conformation is stabilized by an intramolecular hydrogen bond between N5—H5 and the terminal carboxyl (O29) of the molecule (Fig. 1), as predicted by Takasuka et al. (1991). Intermolecular hydrogen bonds are found between atom N9 of the cyanoguanidine group and N10—H10. Thus `clippers' seem to be formed between the molecules. Another intermolecular bond is observed between atom N22 of the pyridine and the carboxyl function. All these groups are thought to be potential anchoring sites for the TXA2 receptor.

In the case of TxSIs, the essential structural features for activity are a basic N atom (a 3-substituted pyridine here) and a carboxylic acid group separated by a distance of 8–10 Å (Iizuka et al., 1981). In (I), a distance of 8.4257 (19) Å is observed between N22 and O30.

In conclusion, two structural features of terbogrel can support its dual action: its hairpin-like conformation for the TRA mode and the two groups separated by 8.4257 (19) Å for the TxSI mode.

Experimental top

Terbogrel (0.173 g; supplier?) was dissolved in acetic acid (1 ml). This solution was then diluted with water (2 ml) and stored for 48 h at room temperature, after which time crystals of (I) formed?.

Refinement top

H atoms H5, H10, H24 and H30 were located in difference Fourier maps and then refined. All other H atoms were calculated geometrically and restrained to ride on their parent atoms, with Ueq(H) fixed to 1.2Ueq of the parent atoms.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1998); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1990); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. ORTEP (Johnson, 1965) representation of (I) showing the hairpin-like conformation. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity.
E-6-[4-(3-tert-butyl-2-cyanoguanidino)phenyl]-6-(3-pyridyl)hex-5-enoic acid top
Crystal data top
C23H27N5O2F(000) = 864
Mr = 405.50Dx = 1.231 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54178 Å
a = 14.934 (1) ÅCell parameters from 25 reflections
b = 10.115 (1) Åθ = 30–40°
c = 15.740 (1) ŵ = 0.65 mm1
β = 113.049 (5)°T = 293 K
V = 2187.8 (3) Å3Polyhedral, colourless
Z = 40.48 × 0.35 × 0.14 mm
Data collection top
Enraf-Nonius CAD4
diffractometer
3571 reflections with I > 2σ(I)
Radiation source: long fine-focus sealed tubeRint = 0.013
Graphite monochromatorθmax = 71.9°, θmin = 3.2°
θ/2θ scansh = 1815
Absorption correction: ψ scan
(North et al., 1968)
k = 812
Tmin = 0.813, Tmax = 0.913l = 019
5986 measured reflections3 standard reflections every 200 reflections
4252 independent reflections intensity decay: 6%
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)] = 0.036H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.105 w = 1/[σ2(Fo2) + (0.0492P)2 + 0.4729P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
4252 reflectionsΔρmax = 0.20 e Å3
288 parametersΔρmin = 0.18 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0021 (2)
Crystal data top
C23H27N5O2V = 2187.8 (3) Å3
Mr = 405.50Z = 4
Monoclinic, P21/cCu Kα radiation
a = 14.934 (1) ŵ = 0.65 mm1
b = 10.115 (1) ÅT = 293 K
c = 15.740 (1) Å0.48 × 0.35 × 0.14 mm
β = 113.049 (5)°
Data collection top
Enraf-Nonius CAD4
diffractometer
3571 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.013
Tmin = 0.813, Tmax = 0.9133 standard reflections every 200 reflections
5986 measured reflections intensity decay: 6%
4252 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0360 restraints
wR(F2) = 0.105H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.20 e Å3
4252 reflectionsΔρmin = 0.18 e Å3
288 parameters
Special details top

Experimental. Tmin and Tmax were generated by HELENA (psi-scan correction)

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
C11.08328 (15)0.0187 (2)0.88663 (13)0.0763 (6)
H1A1.04240.05660.88190.114*
H1B1.12640.03120.94990.114*
H1C1.12070.00420.84990.114*
C21.08166 (13)0.26184 (19)0.85382 (13)0.0662 (5)
H2A1.11600.24710.81440.099*
H2B1.12750.27730.91580.099*
H2C1.04000.33750.83240.099*
C30.96335 (13)0.1680 (2)0.91192 (11)0.0662 (5)
H3A0.92130.24260.88770.099*
H3B1.00770.18660.97400.099*
H3C0.92490.09180.91180.099*
C41.02051 (10)0.14085 (15)0.85219 (9)0.0442 (3)
N50.94693 (8)0.12065 (12)0.75740 (7)0.0399 (3)
H50.8880 (12)0.1047 (15)0.7519 (11)0.049 (4)*
C60.96475 (9)0.10485 (13)0.68113 (9)0.0366 (3)
N71.05604 (8)0.09022 (13)0.69011 (8)0.0465 (3)
C81.07929 (9)0.07551 (16)0.61872 (10)0.0458 (3)
N91.11025 (10)0.05886 (18)0.56317 (10)0.0680 (4)
N100.88886 (8)0.10299 (12)0.59729 (8)0.0405 (3)
H100.9001 (11)0.0617 (16)0.5535 (12)0.053 (4)*
C110.78889 (9)0.12373 (12)0.57780 (8)0.0336 (3)
C120.72172 (9)0.04607 (13)0.50961 (9)0.0388 (3)
H120.74300.01770.47920.047*
C130.62338 (10)0.06382 (14)0.48710 (9)0.0431 (3)
H130.57860.01330.44030.052*
C140.59069 (9)0.15601 (14)0.53340 (9)0.0394 (3)
H140.52440.16530.51890.047*
C150.65697 (9)0.23481 (12)0.60165 (8)0.0333 (3)
C160.75602 (9)0.22091 (12)0.62122 (8)0.0348 (3)
H160.80050.27720.66370.042*
C170.62346 (9)0.33251 (12)0.65423 (9)0.0356 (3)
C180.64529 (9)0.47432 (12)0.64555 (9)0.0358 (3)
C190.63575 (10)0.52835 (14)0.56121 (10)0.0451 (3)
H190.61900.47460.50930.054*
C200.65116 (12)0.66165 (15)0.55459 (11)0.0528 (4)
H200.64560.69860.49860.063*
C210.67480 (11)0.73887 (15)0.63193 (11)0.0515 (4)
H210.68370.82910.62690.062*
N220.68555 (9)0.68985 (12)0.71417 (9)0.0483 (3)
C230.67238 (10)0.56039 (13)0.72015 (10)0.0419 (3)
H230.68190.52560.77770.050*
C240.57394 (10)0.29827 (14)0.70536 (10)0.0413 (3)
H240.5541 (11)0.3688 (15)0.7359 (11)0.048 (4)*
C250.54620 (10)0.16305 (14)0.72486 (10)0.0432 (3)
H25A0.56790.09830.69160.052*
H25B0.47590.15720.70250.052*
C260.59052 (11)0.13039 (14)0.82789 (10)0.0456 (3)
H26A0.57780.20270.86210.055*
H26B0.55930.05190.83890.055*
C270.70013 (11)0.10697 (14)0.86361 (10)0.0489 (3)
H27A0.73130.18470.85150.059*
H27B0.72560.09360.92990.059*
C280.72410 (10)0.01093 (14)0.81872 (10)0.0460 (3)
O290.76994 (9)0.00641 (12)0.77071 (9)0.0641 (3)
O300.68680 (10)0.12204 (11)0.83429 (10)0.0681 (4)
H300.698 (2)0.196 (3)0.7966 (19)0.127 (9)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0775 (12)0.0887 (14)0.0561 (10)0.0253 (11)0.0191 (9)0.0199 (10)
C20.0621 (10)0.0753 (12)0.0648 (11)0.0232 (9)0.0286 (9)0.0221 (9)
C30.0587 (9)0.1049 (14)0.0416 (8)0.0106 (10)0.0268 (7)0.0181 (9)
C40.0399 (7)0.0580 (8)0.0352 (7)0.0012 (6)0.0152 (6)0.0050 (6)
N50.0321 (6)0.0566 (7)0.0349 (6)0.0010 (5)0.0172 (5)0.0047 (5)
C60.0343 (6)0.0419 (7)0.0372 (6)0.0017 (5)0.0178 (5)0.0030 (5)
N70.0339 (6)0.0701 (8)0.0398 (6)0.0033 (5)0.0191 (5)0.0058 (6)
C80.0324 (6)0.0650 (9)0.0422 (7)0.0033 (6)0.0169 (6)0.0052 (7)
N90.0510 (8)0.1096 (12)0.0530 (8)0.0066 (8)0.0306 (7)0.0127 (8)
N100.0340 (6)0.0563 (7)0.0350 (6)0.0059 (5)0.0177 (5)0.0075 (5)
C110.0330 (6)0.0386 (6)0.0326 (6)0.0019 (5)0.0166 (5)0.0008 (5)
C120.0426 (7)0.0412 (7)0.0361 (6)0.0011 (6)0.0191 (6)0.0055 (5)
C130.0403 (7)0.0498 (8)0.0373 (7)0.0068 (6)0.0132 (6)0.0096 (6)
C140.0316 (6)0.0477 (7)0.0392 (7)0.0000 (5)0.0142 (5)0.0013 (6)
C150.0343 (6)0.0339 (6)0.0344 (6)0.0030 (5)0.0164 (5)0.0020 (5)
C160.0326 (6)0.0356 (6)0.0373 (6)0.0012 (5)0.0151 (5)0.0043 (5)
C170.0321 (6)0.0374 (7)0.0380 (6)0.0052 (5)0.0146 (5)0.0008 (5)
C180.0315 (6)0.0380 (7)0.0409 (7)0.0073 (5)0.0174 (5)0.0016 (5)
C190.0470 (7)0.0495 (8)0.0413 (7)0.0059 (6)0.0201 (6)0.0009 (6)
C200.0595 (9)0.0515 (9)0.0512 (8)0.0077 (7)0.0257 (7)0.0146 (7)
C210.0540 (9)0.0393 (7)0.0650 (10)0.0048 (6)0.0274 (8)0.0079 (7)
N220.0529 (7)0.0399 (6)0.0564 (7)0.0013 (5)0.0261 (6)0.0024 (5)
C230.0460 (7)0.0399 (7)0.0435 (7)0.0026 (6)0.0215 (6)0.0001 (6)
C240.0409 (7)0.0419 (7)0.0474 (7)0.0038 (6)0.0243 (6)0.0034 (6)
C250.0416 (7)0.0468 (7)0.0473 (7)0.0057 (6)0.0240 (6)0.0060 (6)
C260.0568 (8)0.0439 (7)0.0466 (8)0.0082 (6)0.0317 (7)0.0079 (6)
C270.0547 (8)0.0460 (8)0.0451 (8)0.0106 (6)0.0185 (7)0.0065 (6)
C280.0457 (7)0.0458 (8)0.0479 (8)0.0062 (6)0.0199 (6)0.0004 (6)
O290.0725 (7)0.0606 (7)0.0773 (8)0.0160 (6)0.0490 (7)0.0096 (6)
O300.0995 (10)0.0443 (6)0.0866 (9)0.0130 (6)0.0646 (8)0.0072 (6)
Geometric parameters (Å, º) top
N10—C61.3621 (17)O29—C281.2028 (17)
N10—C111.4173 (16)O30—C281.3192 (17)
N10—H100.877 (17)O30—H301.01 (3)
C18—C231.3887 (18)C12—H120.9300
C18—C191.3903 (18)C19—C201.379 (2)
C18—C171.4892 (18)C19—H190.9300
C15—C141.3916 (18)N22—C211.3359 (19)
C15—C161.3950 (17)C26—C271.527 (2)
C15—C171.4954 (16)C26—C251.529 (2)
C24—C171.3344 (18)C26—H26A0.9700
C24—C251.4954 (19)C26—H26B0.9700
C24—H240.969 (16)N9—C81.1504 (18)
C16—C111.3916 (16)C25—H25A0.9700
C16—H160.9300C25—H25B0.9700
C11—C121.3901 (18)C28—C271.499 (2)
C6—N71.3226 (16)C21—C201.371 (2)
C6—N51.3371 (16)C21—H210.9300
N5—C41.4804 (17)C27—H27A0.9700
N5—H50.865 (17)C27—H27B0.9700
C4—C11.517 (2)C20—H200.9300
C4—C21.521 (2)C2—H2A0.9600
C4—C31.5219 (19)C2—H2B0.9600
N7—C81.3080 (17)C2—H2C0.9600
C14—C131.3848 (19)C3—H3A0.9600
C14—H140.9300C3—H3B0.9600
C13—C121.3810 (19)C3—H3C0.9600
C13—H130.9300C1—H1A0.9600
C23—N221.3330 (18)C1—H1B0.9600
C23—H230.9300C1—H1C0.9600
C6—N10—C11127.88 (11)C18—C19—H19120.0
C6—N10—H10115.2 (11)C23—N22—C21117.90 (13)
C11—N10—H10114.3 (10)C27—C26—C25112.38 (11)
C23—C18—C19116.61 (12)C27—C26—H26A109.1
C23—C18—C17121.88 (11)C25—C26—H26A109.1
C19—C18—C17121.46 (12)C27—C26—H26B109.1
C14—C15—C16119.01 (11)C25—C26—H26B109.1
C14—C15—C17120.97 (11)H26A—C26—H26B107.9
C16—C15—C17120.01 (11)N9—C8—N7172.12 (15)
C17—C24—C25128.66 (12)C24—C25—C26112.07 (12)
C17—C24—H24117.2 (9)C24—C25—H25A109.2
C25—C24—H24114.1 (9)C26—C25—H25A109.2
C24—C17—C18119.89 (11)C24—C25—H25B109.2
C24—C17—C15123.15 (12)C26—C25—H25B109.2
C18—C17—C15116.94 (10)H25A—C25—H25B107.9
C11—C16—C15120.67 (11)O29—C28—O30122.32 (14)
C11—C16—H16119.7O29—C28—C27124.44 (13)
C15—C16—H16119.7O30—C28—C27113.20 (12)
C12—C11—C16119.46 (11)N22—C21—C20122.71 (14)
C12—C11—N10117.64 (11)N22—C21—H21118.6
C16—C11—N10122.85 (11)C20—C21—H21118.6
N7—C6—N5118.46 (12)C28—C27—C26111.67 (12)
N7—C6—N10122.26 (11)C28—C27—H27A109.3
N5—C6—N10119.28 (11)C26—C27—H27A109.3
C6—N5—C4126.25 (11)C28—C27—H27B109.3
C6—N5—H5116.1 (11)C26—C27—H27B109.3
C4—N5—H5116.9 (11)H27A—C27—H27B107.9
N5—C4—C1111.01 (13)C21—C20—C19118.85 (14)
N5—C4—C2109.39 (12)C21—C20—H20120.6
C1—C4—C2111.49 (14)C19—C20—H20120.6
N5—C4—C3105.83 (11)C4—C2—H2A109.5
C1—C4—C3110.10 (14)C4—C2—H2B109.5
C2—C4—C3108.84 (13)H2A—C2—H2B109.5
C8—N7—C6122.01 (12)C4—C2—H2C109.5
C13—C14—C15120.08 (12)H2A—C2—H2C109.5
C13—C14—H14120.0H2B—C2—H2C109.5
C15—C14—H14120.0C4—C3—H3A109.5
C12—C13—C14120.74 (12)C4—C3—H3B109.5
C12—C13—H13119.6H3A—C3—H3B109.5
C14—C13—H13119.6C4—C3—H3C109.5
N22—C23—C18123.94 (13)H3A—C3—H3C109.5
N22—C23—H23118.0H3B—C3—H3C109.5
C18—C23—H23118.0C4—C1—H1A109.5
C28—O30—H30109.9 (15)C4—C1—H1B109.5
C13—C12—C11119.87 (11)H1A—C1—H1B109.5
C13—C12—H12120.1C4—C1—H1C109.5
C11—C12—H12120.1H1A—C1—H1C109.5
C20—C19—C18119.93 (14)H1B—C1—H1C109.5
C20—C19—H19120.0
C25—C24—C17—C18178.61 (13)N5—C6—N7—C8179.36 (14)
C25—C24—C17—C153.1 (2)N10—C6—N7—C81.3 (2)
C23—C18—C17—C2440.04 (18)C16—C15—C14—C131.13 (19)
C19—C18—C17—C24137.36 (14)C17—C15—C14—C13178.39 (12)
C23—C18—C17—C15141.58 (12)C15—C14—C13—C121.9 (2)
C19—C18—C17—C1541.02 (17)C19—C18—C23—N222.7 (2)
C14—C15—C17—C2459.98 (18)C17—C18—C23—N22174.80 (12)
C16—C15—C17—C24119.53 (14)C14—C13—C12—C111.7 (2)
C14—C15—C17—C18118.34 (13)C16—C11—C12—C131.50 (19)
C16—C15—C17—C1862.15 (16)N10—C11—C12—C13179.04 (12)
C14—C15—C16—C114.34 (18)C23—C18—C19—C201.25 (19)
C17—C15—C16—C11175.18 (11)C17—C18—C19—C20176.27 (12)
C15—C16—C11—C124.54 (19)C18—C23—N22—C212.1 (2)
C15—C16—C11—N10178.06 (11)C6—N7—C8—N9169.1 (13)
C6—N10—C11—C12141.37 (14)C17—C24—C25—C26118.85 (16)
C6—N10—C11—C1641.2 (2)C27—C26—C25—C2471.72 (15)
C11—N10—C6—N7176.67 (13)C23—N22—C21—C200.1 (2)
C11—N10—C6—N54.0 (2)O29—C28—C27—C26116.81 (17)
N7—C6—N5—C48.4 (2)O30—C28—C27—C2660.95 (17)
N10—C6—N5—C4172.22 (13)C25—C26—C27—C2863.41 (16)
C6—N5—C4—C166.44 (18)N22—C21—C20—C191.4 (2)
C6—N5—C4—C257.01 (18)C18—C19—C20—C210.7 (2)
C6—N5—C4—C3174.12 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AH···AD···AD—H···A
N5—H5···O292.206 (18)3.019 (2)156.4 (14)
N10—H10···N9i2.159 (17)3.014 (2)165.0 (16)
O30—H30···N22ii1.69 (3)2.677 (2)164 (3)
Symmetry codes: (i) x+2, y, z+1; (ii) x, y1, z.

Experimental details

Crystal data
Chemical formulaC23H27N5O2
Mr405.50
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)14.934 (1), 10.115 (1), 15.740 (1)
β (°) 113.049 (5)
V3)2187.8 (3)
Z4
Radiation typeCu Kα
µ (mm1)0.65
Crystal size (mm)0.48 × 0.35 × 0.14
Data collection
DiffractometerEnraf-Nonius CAD4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.813, 0.913
No. of measured, independent and
observed [I > 2σ(I)] reflections
5986, 4252, 3571
Rint0.013
(sin θ/λ)max1)0.616
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.105, 1.05
No. of reflections4252
No. of parameters288
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.20, 0.18

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, HELENA (Spek, 1997), SIR97 (Altomare et al., 1998), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 1990), SHELXL97.

Hydrogen-bond geometry (Å, º) top
D—H···AH···AD···AD—H···A
N5—H5···O292.206 (18)3.019 (2)156.4 (14)
N10—H10···N9i2.159 (17)3.014 (2)165.0 (16)
O30—H30···N22ii1.69 (3)2.677 (2)164 (3)
Symmetry codes: (i) x+2, y, z+1; (ii) x, y1, z.
 

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