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

Koch, P.; Schollmeyer, D.; Laufer, S.

doi:10.1107/S1600536809037295

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 65| Part 10| October 2009| Page o2512

doi:10.1107/S1600536809037295

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

Pierre Koch,^a Dieter Schollmeyer ^b and Stefan Laufer ^a ^*

^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 π–π 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 ).

Experimental

Crystal data

C₁₈H₁₁FN₄
M_r = 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 ) T_min = 0.675, T_max = 0.949
2766 measured reflections
2677 independent reflections
2309 reflections with I > 2σ(I)
R_int = 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
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ); cell refinement: CAD-4 Software; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809037295/nc2158sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809037295/nc2158Isup2.hkl

checkCIF report

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).

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

	Fig. 1. Synthesis of I and II.
	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

C₁₈H₁₁FN₄	F(000) = 624
M_r = 302.31	D_x = 1.419 Mg m⁻³
Monoclinic, P2₁/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 17.222 (9) Å	θ = 35–50°
b = 11.2199 (12) Å	µ = 0.80 mm⁻¹
c = 7.329 (4) Å	T = 193 K
β = 91.80 (3)°	Plate, yellow
V = 1415.4 (10) Å³	0.64 × 0.51 × 0.06 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	2309 reflections with I > 2σ(I)
Radiation source: rotating anode	R_int = 0.029
Graphite monochromator	θ_max = 70.1°, θ_min = 2.6°
ω/2θ scans	h = 0→20
Absorption correction: numerical (CORINC; Dräger & Gattow, 1971)	k = 0→13
T_min = 0.675, T_max = 0.949	l = −8→8
2766 measured reflections	3 standard reflections every 60 min
2677 independent reflections	intensity decay: 2%

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.046	H-atom parameters constrained
wR(F²) = 0.134	w = 1/[σ²(F_o²) + (0.0797P)² + 0.3717P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max < 0.001
2677 reflections	Δρ_max = 0.22 e Å⁻³
209 parameters	Δρ_min = −0.24 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0012 (4)

Crystal data top

C₁₈H₁₁FN₄	V = 1415.4 (10) Å³
M_r = 302.31	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 17.222 (9) Å	µ = 0.80 mm⁻¹
b = 11.2199 (12) Å	T = 193 K
c = 7.329 (4) Å	0.64 × 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)	R_int = 0.029
T_min = 0.675, T_max = 0.949	3 standard reflections every 60 min
2766 measured reflections	intensity decay: 2%
2677 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	0 restraints
wR(F²) = 0.134	H-atom parameters constrained
S = 1.07	Δρ_max = 0.22 e Å⁻³
2677 reflections	Δρ_min = −0.24 e Å⁻³
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

	x	y	z	U_iso*/U_eq
C1	0.30818 (9)	0.56244 (13)	0.5692 (2)	0.0294 (4)
N2	0.37936 (8)	0.58947 (12)	0.62301 (19)	0.0323 (3)
C3	0.39843 (9)	0.70720 (14)	0.6323 (2)	0.0317 (4)
N4	0.47243 (8)	0.73360 (13)	0.6904 (2)	0.0386 (4)
C5	0.48914 (10)	0.84780 (17)	0.7036 (2)	0.0419 (4)
H5	0.5405	0.8683	0.7432	0.050*
C6	0.43761 (11)	0.94200 (16)	0.6641 (2)	0.0409 (4)
H6	0.4539	1.0223	0.6795	0.049*
C7	0.36428 (10)	0.91673 (14)	0.6039 (2)	0.0362 (4)
H7	0.3283	0.9786	0.5750	0.043*
C8	0.34280 (9)	0.79530 (14)	0.5851 (2)	0.0307 (4)
N9	0.27022 (8)	0.76613 (11)	0.52296 (18)	0.0312 (3)
C10	0.25245 (9)	0.65216 (13)	0.5120 (2)	0.0291 (3)
C11	0.28858 (9)	0.43306 (14)	0.5734 (2)	0.0315 (4)
C12	0.22105 (10)	0.39077 (15)	0.6474 (2)	0.0386 (4)
H12	0.1837	0.4445	0.6930	0.046*
C13	0.20869 (11)	0.26876 (16)	0.6541 (3)	0.0420 (4)
H13	0.1619	0.2412	0.7048	0.050*
N14	0.25842 (9)	0.18762 (13)	0.5938 (2)	0.0435 (4)
C15	0.32369 (11)	0.22990 (15)	0.5235 (2)	0.0402 (4)
H15	0.3602	0.1741	0.4801	0.048*
C16	0.34126 (10)	0.34977 (14)	0.5101 (2)	0.0344 (4)
H16	0.3885	0.3749	0.4585	0.041*
C17	0.17368 (9)	0.62393 (13)	0.4370 (2)	0.0293 (3)
C18	0.16111 (9)	0.53902 (13)	0.3005 (2)	0.0333 (4)
H18	0.2036	0.4945	0.2571	0.040*
C19	0.08724 (10)	0.51921 (15)	0.2280 (3)	0.0398 (4)
H19	0.0786	0.4614	0.1348	0.048*
C20	0.02664 (10)	0.58435 (16)	0.2928 (3)	0.0410 (4)
C21	0.03648 (10)	0.66822 (17)	0.4283 (3)	0.0446 (4)
H21	−0.0066	0.7112	0.4724	0.054*
C22	0.11058 (10)	0.68841 (15)	0.4987 (2)	0.0379 (4)
H22	0.1187	0.7472	0.5906	0.046*
F23	−0.04531 (7)	0.56622 (13)	0.21986 (18)	0.0642 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0316 (8)	0.0300 (8)	0.0268 (8)	0.0022 (6)	0.0028 (6)	0.0011 (6)
N2	0.0312 (7)	0.0329 (7)	0.0329 (7)	0.0013 (5)	0.0011 (5)	0.0018 (5)
C3	0.0319 (8)	0.0350 (8)	0.0283 (8)	−0.0016 (6)	0.0036 (6)	−0.0013 (6)
N4	0.0326 (7)	0.0447 (8)	0.0384 (8)	−0.0024 (6)	−0.0008 (6)	−0.0001 (6)
C5	0.0346 (9)	0.0514 (10)	0.0397 (10)	−0.0121 (7)	0.0005 (7)	−0.0046 (8)
C6	0.0436 (10)	0.0399 (9)	0.0396 (10)	−0.0126 (7)	0.0097 (8)	−0.0075 (7)
C7	0.0384 (9)	0.0304 (8)	0.0403 (10)	−0.0025 (6)	0.0081 (7)	−0.0029 (7)
C8	0.0312 (8)	0.0312 (8)	0.0299 (8)	−0.0019 (6)	0.0055 (6)	−0.0026 (6)
N9	0.0317 (7)	0.0280 (7)	0.0342 (7)	0.0007 (5)	0.0031 (5)	−0.0007 (5)
C10	0.0311 (8)	0.0279 (7)	0.0284 (8)	0.0009 (6)	0.0040 (6)	0.0000 (6)
C11	0.0338 (8)	0.0305 (8)	0.0298 (8)	0.0012 (6)	−0.0030 (6)	0.0046 (6)
C12	0.0367 (9)	0.0374 (9)	0.0418 (10)	0.0034 (7)	0.0020 (7)	0.0084 (7)
C13	0.0401 (9)	0.0421 (9)	0.0435 (10)	−0.0070 (7)	−0.0002 (7)	0.0115 (8)
N14	0.0523 (9)	0.0337 (7)	0.0443 (9)	−0.0024 (6)	−0.0008 (7)	0.0060 (6)
C15	0.0499 (10)	0.0308 (8)	0.0399 (10)	0.0044 (7)	0.0016 (8)	0.0018 (7)
C16	0.0366 (8)	0.0330 (8)	0.0334 (9)	0.0014 (6)	−0.0008 (6)	0.0029 (6)
C17	0.0312 (8)	0.0257 (7)	0.0311 (8)	0.0005 (6)	0.0016 (6)	0.0029 (6)
C18	0.0365 (8)	0.0282 (7)	0.0352 (9)	0.0005 (6)	0.0013 (7)	0.0009 (6)
C19	0.0453 (10)	0.0345 (8)	0.0394 (10)	−0.0070 (7)	−0.0033 (7)	−0.0014 (7)
C20	0.0295 (8)	0.0503 (10)	0.0431 (10)	−0.0074 (7)	−0.0027 (7)	0.0052 (8)
C21	0.0329 (9)	0.0533 (10)	0.0480 (11)	0.0059 (7)	0.0050 (8)	−0.0022 (8)
C22	0.0358 (9)	0.0388 (9)	0.0393 (10)	0.0027 (7)	0.0016 (7)	−0.0060 (7)
F23	0.0348 (6)	0.0915 (10)	0.0656 (8)	−0.0096 (6)	−0.0107 (5)	−0.0054 (7)

Geometric parameters (Å, º) top

C1—N2	1.311 (2)	C12—H12	0.9500
C1—C10	1.444 (2)	C13—N14	1.335 (2)
C1—C11	1.491 (2)	C13—H13	0.9500
N2—C3	1.362 (2)	N14—C15	1.338 (2)
C3—N4	1.363 (2)	C15—C16	1.383 (2)
C3—C8	1.412 (2)	C15—H15	0.9500
N4—C5	1.316 (2)	C16—H16	0.9500
C5—C6	1.404 (3)	C17—C22	1.393 (2)
C5—H5	0.9500	C17—C18	1.393 (2)
C6—C7	1.355 (3)	C18—C19	1.381 (2)
C6—H6	0.9500	C18—H18	0.9500
C7—C8	1.417 (2)	C19—C20	1.371 (3)
C7—H7	0.9500	C19—H19	0.9500
C8—N9	1.357 (2)	C20—F23	1.349 (2)
N9—C10	1.3167 (19)	C20—C21	1.375 (3)
C10—C17	1.482 (2)	C21—C22	1.380 (2)
C11—C12	1.383 (2)	C21—H21	0.9500
C11—C16	1.392 (2)	C22—H22	0.9500
C12—C13	1.386 (2)

N2—C1—C10	122.18 (14)	C13—C12—H12	120.5
N2—C1—C11	115.41 (13)	N14—C13—C12	124.13 (17)
C10—C1—C11	122.41 (14)	N14—C13—H13	117.9
C1—N2—C3	117.45 (14)	C12—C13—H13	117.9
N2—C3—N4	116.60 (14)	C13—N14—C15	116.18 (15)
N2—C3—C8	120.38 (15)	N14—C15—C16	124.10 (17)
N4—C3—C8	123.01 (15)	N14—C15—H15	118.0
C5—N4—C3	115.75 (15)	C16—C15—H15	118.0
N4—C5—C6	125.61 (16)	C15—C16—C11	118.86 (16)
N4—C5—H5	117.2	C15—C16—H16	120.6
C6—C5—H5	117.2	C11—C16—H16	120.6
C7—C6—C5	119.09 (16)	C22—C17—C18	118.88 (15)
C7—C6—H6	120.5	C22—C17—C10	118.89 (14)
C5—C6—H6	120.5	C18—C17—C10	122.15 (14)
C6—C7—C8	118.08 (16)	C19—C18—C17	120.45 (16)
C6—C7—H7	121.0	C19—C18—H18	119.8
C8—C7—H7	121.0	C17—C18—H18	119.8
N9—C8—C3	121.61 (14)	C20—C19—C18	118.86 (16)
N9—C8—C7	119.96 (14)	C20—C19—H19	120.6
C3—C8—C7	118.43 (15)	C18—C19—H19	120.6
C10—N9—C8	117.69 (13)	F23—C20—C19	118.82 (17)
N9—C10—C1	120.54 (14)	F23—C20—C21	118.69 (17)
N9—C10—C17	116.01 (13)	C19—C20—C21	122.49 (16)
C1—C10—C17	123.44 (13)	C20—C21—C22	118.28 (17)
C12—C11—C16	117.74 (15)	C20—C21—H21	120.9
C12—C11—C1	122.42 (15)	C22—C21—H21	120.9
C16—C11—C1	119.75 (15)	C21—C22—C17	121.02 (16)
C11—C12—C13	118.99 (16)	C21—C22—H22	119.5
C11—C12—H12	120.5	C17—C22—H22	119.5

C10—C1—N2—C3	3.3 (2)	N2—C1—C11—C16	−43.4 (2)
C11—C1—N2—C3	−176.00 (14)	C10—C1—C11—C16	137.36 (16)
C1—N2—C3—N4	179.30 (14)	C16—C11—C12—C13	−0.4 (2)
C1—N2—C3—C8	0.0 (2)	C1—C11—C12—C13	−176.96 (16)
N2—C3—N4—C5	−178.11 (15)	C11—C12—C13—N14	0.3 (3)
C8—C3—N4—C5	1.2 (2)	C12—C13—N14—C15	0.0 (3)
C3—N4—C5—C6	0.3 (3)	C13—N14—C15—C16	−0.3 (3)
N4—C5—C6—C7	−1.3 (3)	N14—C15—C16—C11	0.2 (3)
C5—C6—C7—C8	0.6 (3)	C12—C11—C16—C15	0.2 (2)
N2—C3—C8—N9	−2.6 (2)	C1—C11—C16—C15	176.82 (15)
N4—C3—C8—N9	178.18 (15)	N9—C10—C17—C22	−45.2 (2)
N2—C3—C8—C7	177.49 (15)	C1—C10—C17—C22	135.38 (17)
N4—C3—C8—C7	−1.8 (2)	N9—C10—C17—C18	131.58 (16)
C6—C7—C8—N9	−179.16 (15)	C1—C10—C17—C18	−47.8 (2)
C6—C7—C8—C3	0.8 (2)	C22—C17—C18—C19	−0.1 (2)
C3—C8—N9—C10	1.6 (2)	C10—C17—C18—C19	−176.90 (15)
C7—C8—N9—C10	−178.43 (15)	C17—C18—C19—C20	−0.1 (2)
C8—N9—C10—C1	1.6 (2)	C18—C19—C20—F23	179.01 (16)
C8—N9—C10—C17	−177.79 (13)	C18—C19—C20—C21	−0.5 (3)
N2—C1—C10—N9	−4.3 (2)	F23—C20—C21—C22	−178.31 (17)
C11—C1—C10—N9	174.95 (15)	C19—C20—C21—C22	1.2 (3)
N2—C1—C10—C17	175.07 (14)	C20—C21—C22—C17	−1.3 (3)
C11—C1—C10—C17	−5.7 (2)	C18—C17—C22—C21	0.8 (3)
N2—C1—C11—C12	133.14 (17)	C10—C17—C22—C21	177.73 (16)
C10—C1—C11—C12	−46.1 (2)

Experimental details

Crystal data
Chemical formula	C₁₈H₁₁FN₄
M_r	302.31
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	193
a, b, c (Å)	17.222 (9), 11.2199 (12), 7.329 (4)
β (°)	91.80 (3)
V (Å³)	1415.4 (10)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.80
Crystal size (mm)	0.64 × 0.51 × 0.06

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	Numerical (CORINC; Dräger & Gattow, 1971)
T_min, T_max	0.675, 0.949
No. of measured, independent and observed [I > 2σ(I)] reflections	2766, 2677, 2309
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.610

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.134, 1.07
No. of reflections	2677
No. of parameters	209
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	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

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