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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 64| Part 3| March 2008| Page o547
doi:10.1107/S1600536808003073

3-Benzyl-5-bromo­pyrazin-2(1H)-one

Jo Alena and Liliana Dobrzańskab*

aMolecular Design & Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, and bDepartment of Chemistry, University of Stellenbosch, Private Bag X1, Matieland, South Africa
*Correspondence e-mail: lianger@sun.ac.za

(Received 11 December 2007; accepted 28 January 2008; online 6 February 2008)

In the title compound, C11H9BrN2O, the mol­ecules are linked into R22(8) dimers by paired N—H⋯O hydrogen bonds and these dimers are further stacked into columns along the c axis by π–π inter­actions between pyrazinone rings [centroid–centroid distance = 3.544 Å; the dihedral angle between the planes of these rings is 7.51 (16)°]. The title compound is a precursor for agents with potential use as pharmaceuticals.

Related literature

For related literature, see: Betancur et al. (1997[Betancur, C., Azzi, M. & Rostène, W. (1997). Trends Pharmacol. Sci. 18, 372-386.]); Harrison et al. (1994[Harrison, T., Williams, B. J. & Swain, C. J. (1994). Bioorg. Med. Chem. Lett. 4, 2733-2734.]); Rombouts et al. (2001[Rombouts, F. J. R., De Borggraeve, W. M., Toppet, S. M., Compernolle, F. & Hoornaert, G. J. (2001). Tetrahedron Lett. 42, 7397-7399.], 2003[Rombouts, F. J. R., Van den Bossche, J., Toppet, S. M., Compernolle, F. & Hoornaert, G. J. (2003). Tetrahedron, 59, 4721-4731.]); Snider et al. (1991[Snider, R. M., Constantine, J. W., Lowe, J. A. III, Longo, K. P., Lebel, W. S., Woody, H. A., Drozda, S. E., Desai, M. C., Vinick, F. J., Spencer, R. W. & Hess, H.-J. (1991). Science, 251, 435-437.]).

[Scheme 1]

Experimental

Crystal data

  • C11H9BrN2O

  • Mr = 265.11

  • Orthorhombic, P c c n

  • a = 12.0408 (16) Å

  • b = 24.273 (3) Å

  • c = 7.0428 (10) Å

  • V = 2058.4 (5) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 3.97 mm−1

  • T = 100 (2) K

  • 0.28 × 0.16 × 0.14 mm
Data collection

  • Bruker APEX CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1997[Sheldrick, G. M. (1997). SADABS. University of Göttingen, Germany.]) Tmin = 0.383, Tmax = 0.576

  • 9901 measured reflections

  • 1825 independent reflections

  • 1242 reflections with I > 2σ(I)

  • Rint = 0.097
Refinement

  • R[F2 > 2σ(F2)] = 0.051

  • wR(F2) = 0.120

  • S = 0.99

  • 1825 reflections

  • 136 parameters

  • H-atom parameters constrained

  • Δρmax = 0.71 e Å−3

  • Δρmin = −0.55 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N3—H3⋯O8i 0.88 1.88 2.760 (5) 171
Symmetry code: (i) [-x+{\script{3\over 2}}, -y+{\script{3\over 2}}, z].

Data collection: SMART (Bruker, 2001[Bruker (2001). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2002[Bruker (2002). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; 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: X-SEED (Barbour, 2001[Barbour, L. J. (2001). J. Supramol. Chem. 1, 189-191.]; Atwood & Barbour, 2003[Atwood, J. L. & Barbour, L. J. (2003). Cryst. Growth Des. 3, 3-8.]); software used to prepare material for publication: X-SEED;.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808003073/kp2155sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808003073/kp2155Isup2.hkl

checkCIF report


Comment top

During the early nineties Pfizer (Snider et al., 1991) and Merck (Harrison et al., 1994) optimized a type of compounds (Betancur et al., 1997) that may be of therapeutic use in the treatment of chronic pain, inflammation, depression, emesis, and asthma. (I) can be converted into similar agents with potential biological activity (Rombouts et al., 2001; Rombouts et al., 2003). The molecular structure is given in Fig. 1. The dihedral angle between the planes of the benzene ring (C10—C15) and the pyrazinone ring (C1—N6) is 67.1 (2)°. The r.m.s deviation from the mean plane for the C10—C15 benzene ring is 0.004 Å [maximum deviation = 0.007 (4) Å for atom C13]. For the pyrazinone ring the corresponding value is 0.009 Å [maximum deviation = 0.015 (4) Å for atom C5]. In the crystal packing around a twofold axes hydrogen-bonded dimers are formed through N3—H···O8ihydrogen bond [symmetry code: (i) 3/2 - x, 3/2 - y, z; distance of 2.760 (5) Å (Table 1, Fig. 2). These dimers are stacked into columns by π-π interactions between pyrazinone rings along the c axis [centroid···centroid distances = 3.544 Å; symmetry codes: (ii) 3/2 - x, y, 1/2 + z and (iii) 3/2 - x, y, -1/2 + z] (Fig. 3). There are no direction-specific interactions between stacked columns (Fig. 4).

Related literature top

For related literature, see: Betancur et al. (1997); Harrison et al. (1994); Rombouts et al. (2001, 2003); Snider et al. (1991).

Experimental top

105 mg (0.6 mmol) N-bromosuccinimide was added to an ice-cooled solution (273 K) of 100 mg (0.5 mmol) 3-benzyl-2(1H)-pyrazinone in anhydrous DMF and the mixture was stirred for 2 h at 273 K under inert atmosphere. After extraction with dichloromethane (3x), the organic layer was washed with water, dried over magnesium sulfate and concentrated in vacuo. The crude residue was purified by HPLC (column: Bio-Sil D90–10/250x10mm; Ref 614–0183; eluens: DCM/EtOAc 85:15; flow rate: 3 mL/min) to afford the desired product in 74% yield. IR (KBr, cm-1): 1640.9 (C=O), 1583.4 (C=N); 1H-NMR (300 MHz, CDCl3): 7.5–7.1 (m, 7H, NH + ArH), 4.1 (s, 2H, CH2); 13C-NMR (75 MHz, CDCl3): 136.3 (CO), 129.4–129.3–128.8–128.5–127.8–126.8 (9ArC), 39.3 (CH2); m/z (E.I., %): 264 (M+, 81), 263 (M+ - H, 62), 206 (C8H15OBr, 100), 185 (C4H3ON2Br, 74); HRMS (E.I.): exact mass calcd for C11H9N2OBr: 263.98982; found: 263.99082.

Refinement top

H atoms were positioned geometrically (C—H = 0.95 and 0.99 Å; N—H = 0.99 Å) and constrained to ride on their parent atoms; Uiso(H) values were fixed at 1.2 times Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001; Atwood & Barbour, 2003); software used to prepare material for publication: X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radii.
[Figure 2] Fig. 2. Hydrogen-bonded dimer. Hydrogen bonds are shown as dashed lines. The unlabeled molecule is related to the labeled one by the symmetry operation 3/2 - x, 3/2 - y, z.
[Figure 3] Fig. 3. Capped-stick representation showing the π-π stacking geometry of (I) (dashed orange lines).
[Figure 4] Fig. 4. The packing of (I) viewed down [001].
3-Benzyl-5-bromopyrazin-2(1H)-one top
Crystal data top
C11H9BrN2ODx = 1.711 Mg m−3
Mr = 265.11Melting point: 428 K
Orthorhombic, PccnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2acCell parameters from 862 reflections
a = 12.0408 (16) Åθ = 3.0–18.1°
b = 24.273 (3) ŵ = 3.97 mm−1
c = 7.0428 (10) ÅT = 100 K
V = 2058.4 (5) Å3Block, pale yellow
Z = 80.28 × 0.16 × 0.14 mm
F(000) = 1056
Data collection top
Bruker APEX CCD area-detector
diffractometer		1825 independent reflections
Radiation source: fine-focus sealed tube1242 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.097
ω scansθmax = 25.0°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)		h = −14→14
Tmin = 0.383, Tmax = 0.576k = −28→28
9901 measured reflectionsl = −8→6
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)] = 0.051Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.120H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0603P)2]
where P = (Fo2 + 2Fc2)/3
1825 reflections(Δ/σ)max = 0.001
136 parametersΔρmax = 0.71 e Å−3
0 restraintsΔρmin = −0.55 e Å−3
Crystal data top
C11H9BrN2OV = 2058.4 (5) Å3
Mr = 265.11Z = 8
Orthorhombic, PccnMo Kα radiation
a = 12.0408 (16) ŵ = 3.97 mm−1
b = 24.273 (3) ÅT = 100 K
c = 7.0428 (10) Å0.28 × 0.16 × 0.14 mm
Data collection top
Bruker APEX CCD area-detector
diffractometer		1825 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)		1242 reflections with I > 2σ(I)
Tmin = 0.383, Tmax = 0.576Rint = 0.097
9901 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0510 restraints
wR(F2) = 0.120H-atom parameters constrained
S = 1.00Δρmax = 0.71 e Å−3
1825 reflectionsΔρmin = −0.55 e Å−3
136 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
C10.7911 (5)0.5858 (2)0.1629 (8)0.0200 (13)
C20.8466 (4)0.6322 (2)0.1986 (9)0.0224 (13)
H20.92530.63350.19080.027*
N30.7866 (3)0.67783 (18)0.2467 (6)0.0203 (11)
H30.82250.70860.27080.024*
C40.6734 (5)0.6778 (2)0.2591 (8)0.0210 (13)
C50.6231 (4)0.6248 (2)0.2201 (7)0.0210 (12)
N60.6796 (4)0.58141 (18)0.1693 (7)0.0224 (11)
Br70.86975 (5)0.52084 (2)0.10346 (9)0.0303 (2)
O80.6208 (3)0.71960 (14)0.3066 (6)0.0260 (9)
C90.4979 (4)0.6209 (2)0.2288 (8)0.0248 (14)
H9A0.46970.64790.32230.030*
H9B0.47680.58360.27340.030*
C100.4439 (4)0.6316 (2)0.0387 (8)0.0207 (13)
C110.4358 (4)0.6843 (2)−0.0314 (8)0.0217 (13)
H110.46760.71410.03740.026*
C120.3819 (4)0.6943 (2)−0.2013 (9)0.0299 (14)
H120.37730.7309−0.24870.036*
C130.3350 (5)0.6521 (3)−0.3016 (10)0.0344 (16)
H130.29660.6594−0.41680.041*
C140.3437 (4)0.5990 (3)−0.2346 (9)0.0314 (16)
H140.31260.5694−0.30520.038*
C150.3968 (4)0.5887 (2)−0.0673 (9)0.0268 (15)
H150.40200.5519−0.02200.032*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.027 (3)0.017 (3)0.015 (3)0.004 (2)−0.002 (2)−0.002 (2)
C20.021 (3)0.024 (3)0.022 (3)0.003 (3)−0.002 (3)0.001 (3)
N30.016 (2)0.016 (2)0.028 (3)−0.001 (2)−0.003 (2)0.004 (2)
C40.023 (3)0.022 (3)0.018 (3)−0.004 (3)−0.002 (2)0.004 (3)
C50.021 (3)0.031 (3)0.011 (3)0.001 (3)−0.001 (3)0.008 (2)
N60.025 (3)0.021 (3)0.021 (3)−0.004 (2)−0.003 (2)0.004 (2)
Br70.0358 (4)0.0211 (3)0.0341 (4)0.0062 (3)0.0004 (3)−0.0002 (3)
O80.022 (2)0.024 (2)0.033 (2)−0.0024 (18)0.0019 (19)−0.0004 (19)
C90.022 (3)0.031 (3)0.021 (3)−0.003 (3)0.000 (3)0.007 (3)
C100.013 (3)0.026 (3)0.023 (3)−0.001 (2)0.011 (2)−0.003 (3)
C110.013 (3)0.025 (3)0.027 (3)−0.002 (2)0.012 (3)−0.003 (3)
C120.017 (3)0.036 (3)0.037 (4)0.004 (3)0.001 (3)0.009 (3)
C130.016 (3)0.069 (5)0.018 (3)−0.006 (3)−0.002 (3)0.006 (4)
C140.014 (3)0.043 (4)0.037 (4)−0.004 (3)0.006 (3)−0.007 (3)
C150.019 (3)0.024 (3)0.037 (4)0.004 (3)0.009 (3)−0.002 (3)
Geometric parameters (Å, º) top
C1—C21.334 (7)C9—H9B0.9900
C1—N61.347 (7)C10—C111.375 (7)
C1—Br71.886 (5)C10—C151.401 (8)
C2—N31.365 (6)C11—C121.383 (8)
C2—H20.9500C11—H110.9500
N3—C41.366 (6)C12—C131.366 (8)
N3—H30.8800C12—H120.9500
C4—O81.243 (6)C13—C141.378 (9)
C4—C51.447 (8)C13—H130.9500
C5—N61.305 (7)C14—C151.364 (9)
C5—C91.512 (7)C14—H140.9500
C9—C101.512 (8)C15—H150.9500
C9—H9A0.9900
C2—C1—N6124.0 (5)C10—C9—H9B109.1
C2—C1—Br7119.7 (4)H9A—C9—H9B107.8
N6—C1—Br7116.2 (4)C11—C10—C15118.2 (6)
C1—C2—N3117.8 (5)C11—C10—C9120.5 (5)
C1—C2—H2121.1C15—C10—C9121.2 (5)
N3—C2—H2121.1C10—C11—C12120.5 (6)
C2—N3—C4122.9 (5)C10—C11—H11119.8
C2—N3—H3118.6C12—C11—H11119.8
C4—N3—H3118.6C13—C12—C11120.7 (6)
O8—C4—N3121.7 (5)C13—C12—H12119.7
O8—C4—C5124.3 (5)C11—C12—H12119.7
N3—C4—C5114.0 (5)C12—C13—C14119.5 (6)
N6—C5—C4123.4 (5)C12—C13—H13120.2
N6—C5—C9118.7 (5)C14—C13—H13120.2
C4—C5—C9117.8 (5)C15—C14—C13120.2 (6)
C5—N6—C1117.7 (5)C15—C14—H14119.9
C5—C9—C10112.5 (4)C13—C14—H14119.9
C5—C9—H9A109.1C14—C15—C10120.9 (6)
C10—C9—H9A109.1C14—C15—H15119.6
C5—C9—H9B109.1C10—C15—H15119.6
N6—C1—C2—N30.8 (9)N6—C5—C9—C10−85.6 (6)
Br7—C1—C2—N3−178.0 (4)C4—C5—C9—C1091.2 (6)
C1—C2—N3—C4−0.2 (8)C5—C9—C10—C11−75.6 (6)
C2—N3—C4—O8178.7 (5)C5—C9—C10—C15107.0 (6)
C2—N3—C4—C51.1 (7)C15—C10—C11—C120.5 (8)
O8—C4—C5—N6179.6 (5)C9—C10—C11—C12−177.0 (5)
N3—C4—C5—N6−2.9 (8)C10—C11—C12—C130.5 (8)
O8—C4—C5—C93.0 (8)C11—C12—C13—C14−1.4 (9)
N3—C4—C5—C9−179.5 (5)C12—C13—C14—C151.3 (9)
C4—C5—N6—C13.6 (8)C13—C14—C15—C10−0.4 (8)
C9—C5—N6—C1−179.8 (5)C11—C10—C15—C14−0.5 (8)
C2—C1—N6—C5−2.5 (9)C9—C10—C15—C14177.0 (5)
Br7—C1—N6—C5176.4 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O8i0.881.882.760 (5)171
Symmetry code: (i) −x+3/2, −y+3/2, z.

Experimental details

Crystal data
Chemical formulaC11H9BrN2O
Mr265.11
Crystal system, space groupOrthorhombic, Pccn
Temperature (K)100
a, b, c (Å)12.0408 (16), 24.273 (3), 7.0428 (10)
V (Å3)2058.4 (5)
Z8
Radiation typeMo Kα
µ (mm−1)3.97
Crystal size (mm)0.28 × 0.16 × 0.14
Data collection
DiffractometerBruker APEX CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1997)
Tmin, Tmax0.383, 0.576
No. of measured, independent and
observed [I > 2σ(I)] reflections		9901, 1825, 1242
Rint0.097
(sin θ/λ)max (Å−1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.051, 0.120, 1.00
No. of reflections1825
No. of parameters136
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.71, −0.55

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O8i0.881.882.760 (5)171
Symmetry code: (i) −x+3/2, −y+3/2, z.
 

Acknowledgements

The authors thank the University of Stellenbosch for financial support. JA (Postdoctoral Fellow of the FWO Flanders) thanks the FWO for the fellowship received.

References

First citationAtwood, J. L. & Barbour, L. J. (2003). Cryst. Growth Des. 3, 3–8.  Web of Science CrossRef CAS Google Scholar
 First citationBarbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.  CrossRef CAS Google Scholar
 First citationBetancur, C., Azzi, M. & Rostène, W. (1997). Trends Pharmacol. Sci. 18, 372–386.  CrossRef CAS PubMed Web of Science Google Scholar
 First citationBruker (2001). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationBruker (2002). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationHarrison, T., Williams, B. J. & Swain, C. J. (1994). Bioorg. Med. Chem. Lett. 4, 2733–2734.  CrossRef CAS Web of Science Google Scholar
 First citationRombouts, F. J. R., De Borggraeve, W. M., Toppet, S. M., Compernolle, F. & Hoornaert, G. J. (2001). Tetrahedron Lett. 42, 7397–7399.  Web of Science CrossRef CAS Google Scholar
 First citationRombouts, F. J. R., Van den Bossche, J., Toppet, S. M., Compernolle, F. & Hoornaert, G. J. (2003). Tetrahedron, 59, 4721–4731.  Web of Science CrossRef CAS Google Scholar
 First citationSheldrick, G. M. (1997). SADABS. University of Göttingen, Germany.  Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSnider, R. M., Constantine, J. W., Lowe, J. A. III, Longo, K. P., Lebel, W. S., Woody, H. A., Drozda, S. E., Desai, M. C., Vinick, F. J., Spencer, R. W. & Hess, H.-J. (1991). Science, 251, 435–437.  CrossRef PubMed CAS Web of Science Google Scholar

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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 3| March 2008| Page o547
doi:10.1107/S1600536808003073
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