organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

1-Acetyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one

aLaboratoire de Chimie Organique Appliquée, Université Sidi Mohamed Ben Abdallah, Faculté des Sciences et Techniques, Route d'Immouzzer, BP 2202 Fès, Morocco, bDepartamento de Quimica Inorganica e Organica, ESTCE, Universitat Jaume I, E-12080 Castellon, Spain, cLaboratoire de Chimie Organique Hétérocyclique URAC21, Faculté des Sciences, Université Mohammed V-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco, and dLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: s_dahmani12@yahoo.fr

(Received 30 April 2011; accepted 5 May 2011; online 11 May 2011)

The two fused five- and six-membered rings in the mol­ecule of the title compound, C8H6BrN3O2, are approximately coplanar, the largest deviation from the mean plane being 0.011 (3) Å at the NH atom. The acetyl group is slightly twisted with respect to the imidazo[4,5-b]pyridine system, making a dihedral angle of 2.7 (2)°. In the crystal, adjacent mol­ecules are linked by inter­molecular N—H⋯N and C—H⋯O hydrogen bonds, forming infinite chains.

Related literature

For background information on the pharmacological activities of imidazo[4,5-b]pyridines, see: Kale et al. (2009[Kale, R. P., Shaikh, M. U., Jadhav, G. R. & Gill, C. H. (2009). Tetrahedron Lett. 50, 1780-1782.]); Silverman (2004[Silverman, R. B. (2004). The Organic Chemistry of Drug Design and Drug Action, 2nd ed. Amsterdam: Elsevier Academic Press.]); Cristalli et al. (1995[Cristalli, G., Vittori, S., Eleuteri, A., Volpini, R., Camaioni, E., Lupidi, G., Mohmoud, N., Bevilacqua, F. & Palu, G. (1995). J. Med. Chem. 38, 4019-4025.]); Cundy et al. (1997[Cundy, D. J., Holan, G., Otaegui, M. & Simpson, G. W. (1997). Bioorg. Med. Chem. Lett. 7, 669-674.]); Banie et al. (2007[Banie, H., Sinha, A., Thomas, R. J., Sircar, J. C. & Richards, M. L. (2007). J. Med. Chem. 50, 5984-5993.]); Mader (2008[Mader, M. (2008). Bioorg. Med. Chem. Lett. 18, 179-183.]); Janssens et al. (1985[Janssens, F., Torremans, J., Janssen, M., Stokbroekx, R. A., Luyckx, M. & Janssen, P. A. J. (1985). J. Med. Chem. 28, 1943-1947.]); Bavetsias et al. (2007[Bavetsias, V., Sun, C., Bouloc, N., Reynisson, J., Workman, P., Linardopoulos, S. & McDonald, E. (2007). Bioorg. Med. Chem. Lett. 17, 6567-6571.]); Coates et al. (1993[Coates, W. J., Connolly, B., Dhanak, D., Flynn, S. T. & Worby, A. (1993). J. Med. Chem. 36, 1387-1392.]).

[Scheme 1]

Experimental

Crystal data
  • C8H6BrN3O2

  • Mr = 256.07

  • Triclinic, [P \overline 1]

  • a = 4.8302 (15) Å

  • b = 9.645 (3) Å

  • c = 9.809 (3) Å

  • α = 81.542 (7)°

  • β = 85.735 (7)°

  • γ = 89.676 (8)°

  • V = 450.8 (2) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 4.53 mm−1

  • T = 298 K

  • 0.41 × 0.16 × 0.11 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.423, Tmax = 0.607

  • 2559 measured reflections

  • 1685 independent reflections

  • 1583 reflections with I > 2σ(I)

  • Rint = 0.019

Refinement
  • R[F2 > 2σ(F2)] = 0.028

  • wR(F2) = 0.074

  • S = 1.07

  • 1685 reflections

  • 128 parameters

  • H-atom parameters constrained

  • Δρmax = 0.43 e Å−3

  • Δρmin = −0.48 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2⋯N1i 0.86 2.02 2.877 (3) 175
C3—H3⋯O2ii 0.93 2.56 3.481 (3) 172
Symmetry codes: (i) -x-1, -y+2, -z+2; (ii) -x+1, -y+1, -z+2.

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2 and 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: ORTEPIII (Burnett & Johnson, 1996[Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.]) and ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Imidazo[4,5-b]pyridines represent the major backbone of numerous medical and biochemical agents possessing different chemical and pharmacological features (Kale et al., 2009; Silverman, 2004), which impart them diverse biological properties like antiviral (Cristalli et al.,1995; Cundy et al., 1997; Banie et al., 2007), and anti-inflammatory (Mader, 2008) activity. Substituted imidazo[4,5-b]pyridines have also been tested for their potential selective antihistamine (H1) agents (Janssens et al.,1985). Imidazo[4,5-b]pyridine derivatives were also reported as Aurora kinases (Bavetsias et al., 2007) and cyclic PDE inhibitors (Coates et al.,1993). Importantly,imidazo[4,5-b]pyridine is a structural analogue of purine whose derivatives easily interact with large biomolecules such as DNA, RNA or diverse proteins in vivo.

The molecular plot of the crystal structure of 3-Acetyl-6-bromo-1,3-dihydro- imidazo[4,5-b]pyridin-2-one is shown in Fig.1. The two fused five and six-membered rings building the molecule are nearly planar with the maximum deviation from the mean plane being -0.011 (3) A ° at N2. They form a dihedral angle of 2.7 (2)° with the acetyl group. In the crystal, adjacent molecules are linked by intermolecular N—H···N and C—H···O hydrogen bonding in the way to form infinite chains as shown in Fig. 2 and Table 1.

Related literature top

For background information on the pharmacological activities of imidazo[4,5-b]pyridines, see: Kale et al. (2009); Silverman (2004); Cristalli et al. (1995); Cundy et al. (1997); Banie et al. (2007); Mader (2008); Janssens et al. (1985); Bavetsias et al. (2007); Coates et al. (1993).

Experimental top

To a stirred solution of 6-bromo-1,3-dihydro-imidazo[4,5 - b-]pyridin-2-one (0.2 g; 93.4 mmol), K2CO3 (0.38 g; 2.8 mmol), and tetra n-butyl ammonium bromide (0.03 g; 9.34 10–5 mol) in DMF, acetyl chloride (0.08 ml; 1.12 mmol) was added dropwise. The mixture was heated under reflux for 24 h. After completion of reaction (monitored by TLC), the salt was filtered and the solvent was removed under reduced pressure. The resulting residue was purified by column chromatography on silica gel using (ethylacetate/hexane) (1/1) as eluent. Crystals were isolated after the solvent was allowed to evaporate.

Refinement top

H atoms were located in a difference map and treated as riding with C—H = 0.93 Å for all aromatic H atoms and 0.96 Å for the methyl with Uiso(H) = 1.2 Ueq and Uiso(H) = 1.5 Ueq for the aromatic and methyl respectively.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. : Molecular view of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles of arbitrary radii.
[Figure 2] Fig. 2. : Partial packing view showing the N-H···N and C-H···O hydrogen bonds as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity. [Symmetry codes: (i) -x-1, -y+2, -z+2; (ii) -x+1, -y+1, -z+2].
1-Acetyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one top
Crystal data top
C8H6BrN3O2Z = 2
Mr = 256.07F(000) = 252
Triclinic, P1Dx = 1.887 Mg m3
Hall symbol: -P 1Melting point: 507 K
a = 4.8302 (15) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.645 (3) ÅCell parameters from 1685 reflections
c = 9.809 (3) Åθ = 2.1–26.0°
α = 81.542 (7)°µ = 4.53 mm1
β = 85.735 (7)°T = 298 K
γ = 89.676 (8)°Fiber, colourless
V = 450.8 (2) Å30.41 × 0.16 × 0.11 mm
Data collection top
Bruker APEXII CCD
diffractometer
1685 independent reflections
Radiation source: fine-focus sealed tube1583 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
ϕ and ω scansθmax = 26.0°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 55
Tmin = 0.423, Tmax = 0.607k = 1111
2559 measured reflectionsl = 012
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)] = 0.028Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.074H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0374P)2 + 0.2048P]
where P = (Fo2 + 2Fc2)/3
1685 reflections(Δ/σ)max = 0.001
128 parametersΔρmax = 0.43 e Å3
0 restraintsΔρmin = 0.48 e Å3
Crystal data top
C8H6BrN3O2γ = 89.676 (8)°
Mr = 256.07V = 450.8 (2) Å3
Triclinic, P1Z = 2
a = 4.8302 (15) ÅMo Kα radiation
b = 9.645 (3) ŵ = 4.53 mm1
c = 9.809 (3) ÅT = 298 K
α = 81.542 (7)°0.41 × 0.16 × 0.11 mm
β = 85.735 (7)°
Data collection top
Bruker APEXII CCD
diffractometer
1685 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
1583 reflections with I > 2σ(I)
Tmin = 0.423, Tmax = 0.607Rint = 0.019
2559 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0280 restraints
wR(F2) = 0.074H-atom parameters constrained
S = 1.07Δρmax = 0.43 e Å3
1685 reflectionsΔρmin = 0.48 e Å3
128 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2σ(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
C10.0666 (6)0.9228 (3)0.7492 (3)0.0412 (6)
H10.09120.97890.66540.049*
C20.1373 (5)0.8216 (3)0.7536 (2)0.0371 (5)
C30.1881 (5)0.7340 (3)0.8759 (2)0.0377 (5)
H30.32530.66580.87960.045*
C40.0199 (5)0.7562 (3)0.9904 (2)0.0355 (5)
C50.1838 (5)0.8602 (3)0.9766 (3)0.0372 (5)
C60.2202 (6)0.7636 (3)1.2009 (3)0.0435 (6)
C70.1715 (7)0.5870 (3)1.1871 (3)0.0466 (6)
C80.1168 (8)0.5301 (3)1.3357 (3)0.0588 (8)
H8A0.23480.45101.35900.088*
H8B0.07400.50121.35340.088*
H8C0.15410.60131.39090.088*
N10.2322 (5)0.9436 (2)0.8618 (2)0.0426 (5)
N20.3244 (5)0.8613 (3)1.1034 (2)0.0435 (5)
H20.46010.91641.11910.052*
N30.0003 (5)0.6957 (2)1.1302 (2)0.0395 (5)
O10.2966 (5)0.7398 (2)1.3223 (2)0.0595 (6)
O20.3528 (6)0.5462 (3)1.1138 (2)0.0757 (8)
Br10.35286 (6)0.80290 (3)0.58804 (2)0.04632 (13)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0412 (14)0.0477 (14)0.0338 (13)0.0047 (11)0.0012 (10)0.0033 (10)
C20.0392 (14)0.0439 (13)0.0276 (11)0.0007 (10)0.0057 (10)0.0072 (9)
C30.0387 (14)0.0428 (12)0.0310 (12)0.0059 (10)0.0035 (10)0.0064 (10)
C40.0369 (13)0.0405 (12)0.0283 (11)0.0025 (10)0.0032 (9)0.0050 (9)
C50.0330 (13)0.0449 (13)0.0341 (12)0.0037 (10)0.0031 (10)0.0100 (10)
C60.0405 (15)0.0523 (15)0.0366 (14)0.0057 (11)0.0085 (11)0.0088 (11)
C70.0598 (18)0.0451 (14)0.0325 (13)0.0098 (12)0.0069 (12)0.0034 (10)
C80.078 (2)0.0572 (17)0.0349 (15)0.0131 (15)0.0123 (14)0.0039 (12)
N10.0397 (13)0.0504 (12)0.0371 (12)0.0090 (10)0.0002 (9)0.0059 (9)
N20.0382 (12)0.0550 (13)0.0359 (12)0.0105 (10)0.0076 (9)0.0074 (9)
N30.0417 (12)0.0461 (11)0.0287 (10)0.0075 (9)0.0083 (8)0.0045 (8)
O10.0640 (14)0.0745 (14)0.0354 (11)0.0152 (11)0.0188 (9)0.0049 (9)
O20.0976 (19)0.0822 (16)0.0386 (11)0.0532 (15)0.0185 (11)0.0060 (10)
Br10.0522 (2)0.0565 (2)0.02805 (16)0.00477 (12)0.00836 (11)0.00472 (11)
Geometric parameters (Å, º) top
C1—N11.354 (3)C6—O11.209 (3)
C1—C21.381 (4)C6—N21.363 (4)
C1—H10.9300C6—N31.433 (3)
C2—C31.398 (4)C7—O21.193 (4)
C2—Br11.894 (2)C7—N31.409 (4)
C3—C41.379 (3)C7—C81.486 (4)
C3—H30.9300C8—H8A0.9600
C4—C51.401 (4)C8—H8B0.9600
C4—N31.406 (3)C8—H8C0.9600
C5—N11.319 (3)N2—H20.8600
C5—N21.374 (3)
N1—C1—C2122.6 (2)N2—C6—N3105.9 (2)
N1—C1—H1118.7O2—C7—N3118.5 (2)
C2—C1—H1118.7O2—C7—C8123.7 (3)
C1—C2—C3122.0 (2)N3—C7—C8117.8 (2)
C1—C2—Br1118.30 (19)C7—C8—H8A109.5
C3—C2—Br1119.66 (19)C7—C8—H8B109.5
C4—C3—C2115.1 (2)H8A—C8—H8B109.5
C4—C3—H3122.5C7—C8—H8C109.5
C2—C3—H3122.5H8A—C8—H8C109.5
C3—C4—C5119.2 (2)H8B—C8—H8C109.5
C3—C4—N3134.3 (2)C5—N1—C1115.0 (2)
C5—C4—N3106.5 (2)C6—N2—C5110.9 (2)
N1—C5—N2125.6 (2)C6—N2—H2124.6
N1—C5—C4126.0 (2)C5—N2—H2124.6
N2—C5—C4108.4 (2)C4—N3—C7124.2 (2)
O1—C6—N2127.0 (3)C4—N3—C6108.4 (2)
O1—C6—N3127.1 (3)C7—N3—C6127.4 (2)
N1—C1—C2—C30.5 (5)N1—C5—N2—C6178.9 (3)
N1—C1—C2—Br1179.6 (2)C4—C5—N2—C60.7 (3)
C1—C2—C3—C40.1 (4)C3—C4—N3—C70.3 (5)
Br1—C2—C3—C4179.98 (19)C5—C4—N3—C7179.4 (3)
C2—C3—C4—C50.5 (4)C3—C4—N3—C6179.8 (3)
C2—C3—C4—N3179.2 (3)C5—C4—N3—C60.5 (3)
C3—C4—C5—N10.8 (4)O2—C7—N3—C42.8 (5)
N3—C4—C5—N1178.9 (3)C8—C7—N3—C4177.5 (3)
C3—C4—C5—N2179.5 (2)O2—C7—N3—C6177.1 (3)
N3—C4—C5—N20.7 (3)C8—C7—N3—C62.6 (5)
N2—C5—N1—C1179.9 (3)O1—C6—N3—C4179.6 (3)
C4—C5—N1—C10.5 (4)N2—C6—N3—C40.0 (3)
C2—C1—N1—C50.2 (4)O1—C6—N3—C70.3 (5)
O1—C6—N2—C5179.1 (3)N2—C6—N3—C7179.8 (3)
N3—C6—N2—C50.4 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···N1i0.862.022.877 (3)175
C3—H3···O2ii0.932.563.481 (3)172
Symmetry codes: (i) x1, y+2, z+2; (ii) x+1, y+1, z+2.

Experimental details

Crystal data
Chemical formulaC8H6BrN3O2
Mr256.07
Crystal system, space groupTriclinic, P1
Temperature (K)298
a, b, c (Å)4.8302 (15), 9.645 (3), 9.809 (3)
α, β, γ (°)81.542 (7), 85.735 (7), 89.676 (8)
V3)450.8 (2)
Z2
Radiation typeMo Kα
µ (mm1)4.53
Crystal size (mm)0.41 × 0.16 × 0.11
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.423, 0.607
No. of measured, independent and
observed [I > 2σ(I)] reflections
2559, 1685, 1583
Rint0.019
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.074, 1.07
No. of reflections1685
No. of parameters128
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.43, 0.48

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···N1i0.862.022.877 (3)174.5
C3—H3···O2ii0.932.563.481 (3)171.8
Symmetry codes: (i) x1, y+2, z+2; (ii) x+1, y+1, z+2.
 

References

First citationBanie, H., Sinha, A., Thomas, R. J., Sircar, J. C. & Richards, M. L. (2007). J. Med. Chem. 50, 5984–5993.  Web of Science CrossRef PubMed CAS Google Scholar
First citationBavetsias, V., Sun, C., Bouloc, N., Reynisson, J., Workman, P., Linardopoulos, S. & McDonald, E. (2007). Bioorg. Med. Chem. Lett. 17, 6567–6571.  Web of Science CrossRef PubMed CAS Google Scholar
First citationBruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationBurnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.  Google Scholar
First citationCoates, W. J., Connolly, B., Dhanak, D., Flynn, S. T. & Worby, A. (1993). J. Med. Chem. 36, 1387–1392.  CrossRef CAS PubMed Web of Science Google Scholar
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First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationJanssens, F., Torremans, J., Janssen, M., Stokbroekx, R. A., Luyckx, M. & Janssen, P. A. J. (1985). J. Med. Chem. 28, 1943–1947.  CrossRef CAS PubMed Web of Science Google Scholar
First citationKale, R. P., Shaikh, M. U., Jadhav, G. R. & Gill, C. H. (2009). Tetrahedron Lett. 50, 1780–1782.  Web of Science CrossRef CAS Google Scholar
First citationMader, M. (2008). Bioorg. Med. Chem. Lett. 18, 179–183.  Web of Science CrossRef PubMed CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSilverman, R. B. (2004). The Organic Chemistry of Drug Design and Drug Action, 2nd ed. Amsterdam: Elsevier Academic Press.  Google Scholar

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