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ISSN: 2056-9890

2-(4-Fluoro­phen­yl)-3-(4-pyrid­yl)pyrido[2,3-b]pyrazine

aInstitute of Pharmacy, Department of Pharmaceutical and Medicinal Chemistry, Eberhard-Karls-University Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany, and bDepartment of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, D-55099 Mainz, Germany
*Correspondence e-mail: stefan.laufer@uni-tuebingen.de

(Received 11 September 2009; accepted 15 September 2009; online 26 September 2009)

In the crystal structure of the title compound, C18H11FN4, the pyridopyrazine system makes dihedral angles of 45.51 (7) and 44.75 (7)° with the attached 4-fluoro­phenyl ring and the pyridine ring, respectively. The 4-fluoro­phenyl ring makes a dihedral angle of 54.54 (8)° with the pyridine ring. The pyridine ring part of the pyridopyrazine ring and the pyrazine ring of two c-glide-plane-related mol­ecules form ππ inter­actions. The angle between the planes is 2.09 (7)° and the distance between the centroids is 3.557 (1)Å.

Related literature

For preparation of pyridopyrazines under microwave conditions, see: Zhao et al. (2004[Zhao, Z., Wisnoski, D. D., Wolkenberg, S. E., Leister, W. H., Wang, Y. & Lindsley, C. W. (2004). Tetrahedron Lett. 45, 4873-4876.]).

[Scheme 1]

Experimental

Crystal data
  • C18H11FN4

  • Mr = 302.31

  • Monoclinic, P 21 /c

  • a = 17.222 (9) Å

  • b = 11.2199 (12) Å

  • c = 7.329 (4) Å

  • β = 91.80 (3)°

  • V = 1415.4 (10) Å3

  • Z = 4

  • Cu Kα radiation

  • μ = 0.80 mm−1

  • T = 193 K

  • 0.64 × 0.51 × 0.06 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: numerical (CORINC; Dräger & Gattow, 1971[Dräger, M. & Gattow, G. (1971). Acta Chem. Scand. 25, 761-762.]) Tmin = 0.675, Tmax = 0.949

  • 2766 measured reflections

  • 2677 independent reflections

  • 2309 reflections with I > 2σ(I)

  • Rint = 0.029

  • 3 standard reflections frequency: 60 min intensity decay: 2%

Refinement
  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.134

  • S = 1.07

  • 2677 reflections

  • 209 parameters

  • H-atom parameters constrained

  • Δρmax = 0.22 e Å−3

  • Δρmin = −0.24 e Å−3

Data collection: CAD-4 Software (Enraf–Nonius, 1989[Enraf-Nonius (1989). CAD-4 Software. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 Software; data reduction: CORINC (Dräger & Gattow, 1971[Dräger, M. & Gattow, G. (1971). Acta Chem. Scand. 25, 761-762.]); program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); 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: PLATON.

Supporting information


Comment top

The title compound, 2-(4-fluorophenyl)-3-(pyridin-4-yl)pyrido[3,2-b]pyrazine (II), was prepared in the course of our studies on pyridin-4-yl-substituted pyridopyrazines as potent p38 mitogen-activated protein (MAP) kinase inhibitors.

The microwave-assisted reaction of 1-(4-fluorophenyl)-2-(pyridin-4-yl)ethane-1,2-dione and 2,3-diaminopyridine yields two regioisomers, 3-(4-fluorophenyl)-2-(pyridin-4-yl)pyrido[2,3-b]pyrazine (I) and 2-(4-fluorophenyl)-3-(pyridin-4-yl)pyrido[3,2-b]pyrazine (II) (Figure I). The isomers were separated by flash-chromatography. To identify the two regioisomers x-ray analysis was used. In this article we present the x-ray data of the last eluted isomer II.

As might be expected the 4-fluorophenyl, the pyridine ring as well as the pyridopyrazine ring are planar (Figure 2). The pyridopyrazine ring makes dihedral angles of 45.51 (7)° and 44.75 (7)° to the 4-fluorophenyl ring and the pyridine ring, respectively. The 4-fluorophenyl ring makes a dihedral angle of 54.54 (8)° to the pyridine ring. The pyridine ring part of the pyridopyrazine ring and the pyrazine ring of two by c-glide plane related molecules forms π-π interactions. The angle between the planes is 2.09 (7)° and the distance of the centroids 3.557 (1) Å.

Related literature top

For preparation of pyridopyrazines under microwave conditions, see: Zhao et al. (2004).

Experimental top

1-(4-Fluorophenyl)-2-(pyridin-4-yl)ethane-1,2-dione (113 mg, 0.5 mmol), and 2,3-diaminopyridine (54 mg, 0.5 mmol), and methanol/glacial acetic acid (2 ml, 9:1, V:V) were combined in a reaction vial. The reaction vessel was heated in a microwave reactor for 5 min at 433 K (initial power 250 W), after which a stream of compressed air cooled the reaction vessel to r.t. The solvent was removed under reduced pressure and the residue was purified by flash-chromatography (silica gel, petroleum ether/ethyl acetate 1–4 to 0–1) to yield 65 mg (43%) of II as a colorless solid. Suitable crystals of compound II for X-ray were obtained by slow evaporation at 298 K of a solution of n-hexane - diethyl ether (2–1).

Refinement top

Hydrogen atoms attached to carbons were placed at calculated positions with C—H = 0.95 Å (aromatic C-atom). All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2 times of the Ueq of the parent atom).

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: CORINC (Dräger & Gattow, 1971); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. Synthesis of I and II.
[Figure 2] Fig. 2. View of compound II. Displacement ellipsoids are drawn at the 50% probability level.
2-(4-Fluorophenyl)-3-(4-pyridyl)pyrido[2,3-b]pyrazine top
Crystal data top
C18H11FN4F(000) = 624
Mr = 302.31Dx = 1.419 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 17.222 (9) Åθ = 35–50°
b = 11.2199 (12) ŵ = 0.80 mm1
c = 7.329 (4) ÅT = 193 K
β = 91.80 (3)°Plate, yellow
V = 1415.4 (10) Å30.64 × 0.51 × 0.06 mm
Z = 4
Data collection top
Enraf–Nonius CAD-4
diffractometer
2309 reflections with I > 2σ(I)
Radiation source: rotating anodeRint = 0.029
Graphite monochromatorθmax = 70.1°, θmin = 2.6°
ω/2θ scansh = 020
Absorption correction: numerical
(CORINC; Dräger & Gattow, 1971)
k = 013
Tmin = 0.675, Tmax = 0.949l = 88
2766 measured reflections3 standard reflections every 60 min
2677 independent reflections intensity decay: 2%
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)] = 0.046H-atom parameters constrained
wR(F2) = 0.134 w = 1/[σ2(Fo2) + (0.0797P)2 + 0.3717P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
2677 reflectionsΔρmax = 0.22 e Å3
209 parametersΔρmin = 0.24 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0012 (4)
Crystal data top
C18H11FN4V = 1415.4 (10) Å3
Mr = 302.31Z = 4
Monoclinic, P21/cCu Kα radiation
a = 17.222 (9) ŵ = 0.80 mm1
b = 11.2199 (12) ÅT = 193 K
c = 7.329 (4) Å0.64 × 0.51 × 0.06 mm
β = 91.80 (3)°
Data collection top
Enraf–Nonius CAD-4
diffractometer
2309 reflections with I > 2σ(I)
Absorption correction: numerical
(CORINC; Dräger & Gattow, 1971)
Rint = 0.029
Tmin = 0.675, Tmax = 0.9493 standard reflections every 60 min
2766 measured reflections intensity decay: 2%
2677 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.134H-atom parameters constrained
S = 1.07Δρmax = 0.22 e Å3
2677 reflectionsΔρmin = 0.24 e Å3
209 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
C10.30818 (9)0.56244 (13)0.5692 (2)0.0294 (4)
N20.37936 (8)0.58947 (12)0.62301 (19)0.0323 (3)
C30.39843 (9)0.70720 (14)0.6323 (2)0.0317 (4)
N40.47243 (8)0.73360 (13)0.6904 (2)0.0386 (4)
C50.48914 (10)0.84780 (17)0.7036 (2)0.0419 (4)
H50.54050.86830.74320.050*
C60.43761 (11)0.94200 (16)0.6641 (2)0.0409 (4)
H60.45391.02230.67950.049*
C70.36428 (10)0.91673 (14)0.6039 (2)0.0362 (4)
H70.32830.97860.57500.043*
C80.34280 (9)0.79530 (14)0.5851 (2)0.0307 (4)
N90.27022 (8)0.76613 (11)0.52296 (18)0.0312 (3)
C100.25245 (9)0.65216 (13)0.5120 (2)0.0291 (3)
C110.28858 (9)0.43306 (14)0.5734 (2)0.0315 (4)
C120.22105 (10)0.39077 (15)0.6474 (2)0.0386 (4)
H120.18370.44450.69300.046*
C130.20869 (11)0.26876 (16)0.6541 (3)0.0420 (4)
H130.16190.24120.70480.050*
N140.25842 (9)0.18762 (13)0.5938 (2)0.0435 (4)
C150.32369 (11)0.22990 (15)0.5235 (2)0.0402 (4)
H150.36020.17410.48010.048*
C160.34126 (10)0.34977 (14)0.5101 (2)0.0344 (4)
H160.38850.37490.45850.041*
C170.17368 (9)0.62393 (13)0.4370 (2)0.0293 (3)
C180.16111 (9)0.53902 (13)0.3005 (2)0.0333 (4)
H180.20360.49450.25710.040*
C190.08724 (10)0.51921 (15)0.2280 (3)0.0398 (4)
H190.07860.46140.13480.048*
C200.02664 (10)0.58435 (16)0.2928 (3)0.0410 (4)
C210.03648 (10)0.66822 (17)0.4283 (3)0.0446 (4)
H210.00660.71120.47240.054*
C220.11058 (10)0.68841 (15)0.4987 (2)0.0379 (4)
H220.11870.74720.59060.046*
F230.04531 (7)0.56622 (13)0.21986 (18)0.0642 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0316 (8)0.0300 (8)0.0268 (8)0.0022 (6)0.0028 (6)0.0011 (6)
N20.0312 (7)0.0329 (7)0.0329 (7)0.0013 (5)0.0011 (5)0.0018 (5)
C30.0319 (8)0.0350 (8)0.0283 (8)0.0016 (6)0.0036 (6)0.0013 (6)
N40.0326 (7)0.0447 (8)0.0384 (8)0.0024 (6)0.0008 (6)0.0001 (6)
C50.0346 (9)0.0514 (10)0.0397 (10)0.0121 (7)0.0005 (7)0.0046 (8)
C60.0436 (10)0.0399 (9)0.0396 (10)0.0126 (7)0.0097 (8)0.0075 (7)
C70.0384 (9)0.0304 (8)0.0403 (10)0.0025 (6)0.0081 (7)0.0029 (7)
C80.0312 (8)0.0312 (8)0.0299 (8)0.0019 (6)0.0055 (6)0.0026 (6)
N90.0317 (7)0.0280 (7)0.0342 (7)0.0007 (5)0.0031 (5)0.0007 (5)
C100.0311 (8)0.0279 (7)0.0284 (8)0.0009 (6)0.0040 (6)0.0000 (6)
C110.0338 (8)0.0305 (8)0.0298 (8)0.0012 (6)0.0030 (6)0.0046 (6)
C120.0367 (9)0.0374 (9)0.0418 (10)0.0034 (7)0.0020 (7)0.0084 (7)
C130.0401 (9)0.0421 (9)0.0435 (10)0.0070 (7)0.0002 (7)0.0115 (8)
N140.0523 (9)0.0337 (7)0.0443 (9)0.0024 (6)0.0008 (7)0.0060 (6)
C150.0499 (10)0.0308 (8)0.0399 (10)0.0044 (7)0.0016 (8)0.0018 (7)
C160.0366 (8)0.0330 (8)0.0334 (9)0.0014 (6)0.0008 (6)0.0029 (6)
C170.0312 (8)0.0257 (7)0.0311 (8)0.0005 (6)0.0016 (6)0.0029 (6)
C180.0365 (8)0.0282 (7)0.0352 (9)0.0005 (6)0.0013 (7)0.0009 (6)
C190.0453 (10)0.0345 (8)0.0394 (10)0.0070 (7)0.0033 (7)0.0014 (7)
C200.0295 (8)0.0503 (10)0.0431 (10)0.0074 (7)0.0027 (7)0.0052 (8)
C210.0329 (9)0.0533 (10)0.0480 (11)0.0059 (7)0.0050 (8)0.0022 (8)
C220.0358 (9)0.0388 (9)0.0393 (10)0.0027 (7)0.0016 (7)0.0060 (7)
F230.0348 (6)0.0915 (10)0.0656 (8)0.0096 (6)0.0107 (5)0.0054 (7)
Geometric parameters (Å, º) top
C1—N21.311 (2)C12—H120.9500
C1—C101.444 (2)C13—N141.335 (2)
C1—C111.491 (2)C13—H130.9500
N2—C31.362 (2)N14—C151.338 (2)
C3—N41.363 (2)C15—C161.383 (2)
C3—C81.412 (2)C15—H150.9500
N4—C51.316 (2)C16—H160.9500
C5—C61.404 (3)C17—C221.393 (2)
C5—H50.9500C17—C181.393 (2)
C6—C71.355 (3)C18—C191.381 (2)
C6—H60.9500C18—H180.9500
C7—C81.417 (2)C19—C201.371 (3)
C7—H70.9500C19—H190.9500
C8—N91.357 (2)C20—F231.349 (2)
N9—C101.3167 (19)C20—C211.375 (3)
C10—C171.482 (2)C21—C221.380 (2)
C11—C121.383 (2)C21—H210.9500
C11—C161.392 (2)C22—H220.9500
C12—C131.386 (2)
N2—C1—C10122.18 (14)C13—C12—H12120.5
N2—C1—C11115.41 (13)N14—C13—C12124.13 (17)
C10—C1—C11122.41 (14)N14—C13—H13117.9
C1—N2—C3117.45 (14)C12—C13—H13117.9
N2—C3—N4116.60 (14)C13—N14—C15116.18 (15)
N2—C3—C8120.38 (15)N14—C15—C16124.10 (17)
N4—C3—C8123.01 (15)N14—C15—H15118.0
C5—N4—C3115.75 (15)C16—C15—H15118.0
N4—C5—C6125.61 (16)C15—C16—C11118.86 (16)
N4—C5—H5117.2C15—C16—H16120.6
C6—C5—H5117.2C11—C16—H16120.6
C7—C6—C5119.09 (16)C22—C17—C18118.88 (15)
C7—C6—H6120.5C22—C17—C10118.89 (14)
C5—C6—H6120.5C18—C17—C10122.15 (14)
C6—C7—C8118.08 (16)C19—C18—C17120.45 (16)
C6—C7—H7121.0C19—C18—H18119.8
C8—C7—H7121.0C17—C18—H18119.8
N9—C8—C3121.61 (14)C20—C19—C18118.86 (16)
N9—C8—C7119.96 (14)C20—C19—H19120.6
C3—C8—C7118.43 (15)C18—C19—H19120.6
C10—N9—C8117.69 (13)F23—C20—C19118.82 (17)
N9—C10—C1120.54 (14)F23—C20—C21118.69 (17)
N9—C10—C17116.01 (13)C19—C20—C21122.49 (16)
C1—C10—C17123.44 (13)C20—C21—C22118.28 (17)
C12—C11—C16117.74 (15)C20—C21—H21120.9
C12—C11—C1122.42 (15)C22—C21—H21120.9
C16—C11—C1119.75 (15)C21—C22—C17121.02 (16)
C11—C12—C13118.99 (16)C21—C22—H22119.5
C11—C12—H12120.5C17—C22—H22119.5
C10—C1—N2—C33.3 (2)N2—C1—C11—C1643.4 (2)
C11—C1—N2—C3176.00 (14)C10—C1—C11—C16137.36 (16)
C1—N2—C3—N4179.30 (14)C16—C11—C12—C130.4 (2)
C1—N2—C3—C80.0 (2)C1—C11—C12—C13176.96 (16)
N2—C3—N4—C5178.11 (15)C11—C12—C13—N140.3 (3)
C8—C3—N4—C51.2 (2)C12—C13—N14—C150.0 (3)
C3—N4—C5—C60.3 (3)C13—N14—C15—C160.3 (3)
N4—C5—C6—C71.3 (3)N14—C15—C16—C110.2 (3)
C5—C6—C7—C80.6 (3)C12—C11—C16—C150.2 (2)
N2—C3—C8—N92.6 (2)C1—C11—C16—C15176.82 (15)
N4—C3—C8—N9178.18 (15)N9—C10—C17—C2245.2 (2)
N2—C3—C8—C7177.49 (15)C1—C10—C17—C22135.38 (17)
N4—C3—C8—C71.8 (2)N9—C10—C17—C18131.58 (16)
C6—C7—C8—N9179.16 (15)C1—C10—C17—C1847.8 (2)
C6—C7—C8—C30.8 (2)C22—C17—C18—C190.1 (2)
C3—C8—N9—C101.6 (2)C10—C17—C18—C19176.90 (15)
C7—C8—N9—C10178.43 (15)C17—C18—C19—C200.1 (2)
C8—N9—C10—C11.6 (2)C18—C19—C20—F23179.01 (16)
C8—N9—C10—C17177.79 (13)C18—C19—C20—C210.5 (3)
N2—C1—C10—N94.3 (2)F23—C20—C21—C22178.31 (17)
C11—C1—C10—N9174.95 (15)C19—C20—C21—C221.2 (3)
N2—C1—C10—C17175.07 (14)C20—C21—C22—C171.3 (3)
C11—C1—C10—C175.7 (2)C18—C17—C22—C210.8 (3)
N2—C1—C11—C12133.14 (17)C10—C17—C22—C21177.73 (16)
C10—C1—C11—C1246.1 (2)

Experimental details

Crystal data
Chemical formulaC18H11FN4
Mr302.31
Crystal system, space groupMonoclinic, P21/c
Temperature (K)193
a, b, c (Å)17.222 (9), 11.2199 (12), 7.329 (4)
β (°) 91.80 (3)
V3)1415.4 (10)
Z4
Radiation typeCu Kα
µ (mm1)0.80
Crystal size (mm)0.64 × 0.51 × 0.06
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correctionNumerical
(CORINC; Dräger & Gattow, 1971)
Tmin, Tmax0.675, 0.949
No. of measured, independent and
observed [I > 2σ(I)] reflections
2766, 2677, 2309
Rint0.029
(sin θ/λ)max1)0.610
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.134, 1.07
No. of reflections2677
No. of parameters209
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.22, 0.24

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), CORINC (Dräger & Gattow, 1971), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).

 

References

First citationAltomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationDräger, M. & Gattow, G. (1971). Acta Chem. Scand. 25, 761–762.  Google Scholar
First citationEnraf–Nonius (1989). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationZhao, Z., Wisnoski, D. D., Wolkenberg, S. E., Leister, W. H., Wang, Y. & Lindsley, C. W. (2004). Tetrahedron Lett. 45, 4873–4876.  Web of Science CrossRef CAS Google Scholar

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