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

Dahmani, S.; Kandri Rodi, Y.; Luis, S.V.; Essassi, E.M.; El Ammari, L.

doi:10.1107/S1600536811017004

organic compounds

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Volume 67| Part 6| June 2011| Page o1375

doi:10.1107/S1600536811017004

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

Siham Dahmani,^a ^* Youssef Kandri Rodi,^a Santiago V. Luis,^b El Mokhtar Essassi ^c and Lahcen El Ammari ^d

^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 ); 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

Crystal data

C₈H₆BrN₃O₂
M_r = 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 ) T_min = 0.423, T_max = 0.607
2559 measured reflections
1685 independent reflections
1583 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.074
S = 1.07
1685 reflections
128 parameters
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	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); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811017004/dn2682sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811017004/dn2682Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811017004/dn2682Isup3.cml

checkCIF report

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.

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

	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.
	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

C₈H₆BrN₃O₂	Z = 2
M_r = 256.07	F(000) = 252
Triclinic, P1	D_x = 1.887 Mg m⁻³
Hall symbol: -P 1	Melting point: 507 K
a = 4.8302 (15) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.645 (3) Å	Cell parameters from 1685 reflections
c = 9.809 (3) Å	θ = 2.1–26.0°
α = 81.542 (7)°	µ = 4.53 mm⁻¹
β = 85.735 (7)°	T = 298 K
γ = 89.676 (8)°	Fiber, colourless
V = 450.8 (2) Å³	0.41 × 0.16 × 0.11 mm

Data collection top

Bruker APEXII CCD diffractometer	1685 independent reflections
Radiation source: fine-focus sealed tube	1583 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
ϕ and ω scans	θ_max = 26.0°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −5→5
T_min = 0.423, T_max = 0.607	k = −11→11
2559 measured reflections	l = 0→12

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.074	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0374P)² + 0.2048P] where P = (F_o² + 2F_c²)/3
1685 reflections	(Δ/σ)_max = 0.001
128 parameters	Δρ_max = 0.43 e Å⁻³
0 restraints	Δρ_min = −0.48 e Å⁻³

Crystal data top

C₈H₆BrN₃O₂	γ = 89.676 (8)°
M_r = 256.07	V = 450.8 (2) Å³
Triclinic, P1	Z = 2
a = 4.8302 (15) Å	Mo Kα radiation
b = 9.645 (3) Å	µ = 4.53 mm⁻¹
c = 9.809 (3) Å	T = 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)
T_min = 0.423, T_max = 0.607	R_int = 0.019
2559 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.074	H-atom parameters constrained
S = 1.07	Δρ_max = 0.43 e Å⁻³
1685 reflections	Δρ_min = −0.48 e Å⁻³
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

	x	y	z	U_iso*/U_eq
C1	−0.0666 (6)	0.9228 (3)	0.7492 (3)	0.0412 (6)
H1	−0.0912	0.9789	0.6654	0.049*
C2	0.1373 (5)	0.8216 (3)	0.7536 (2)	0.0371 (5)
C3	0.1881 (5)	0.7340 (3)	0.8759 (2)	0.0377 (5)
H3	0.3253	0.6658	0.8796	0.045*
C4	0.0199 (5)	0.7562 (3)	0.9904 (2)	0.0355 (5)
C5	−0.1838 (5)	0.8602 (3)	0.9766 (3)	0.0372 (5)
C6	−0.2202 (6)	0.7636 (3)	1.2009 (3)	0.0435 (6)
C7	0.1715 (7)	0.5870 (3)	1.1871 (3)	0.0466 (6)
C8	0.1168 (8)	0.5301 (3)	1.3357 (3)	0.0588 (8)
H8A	0.2348	0.4510	1.3590	0.088*
H8B	−0.0740	0.5012	1.3534	0.088*
H8C	0.1541	0.6013	1.3909	0.088*
N1	−0.2322 (5)	0.9436 (2)	0.8618 (2)	0.0426 (5)
N2	−0.3244 (5)	0.8613 (3)	1.1034 (2)	0.0435 (5)
H2	−0.4601	0.9164	1.1191	0.052*
N3	−0.0003 (5)	0.6957 (2)	1.1302 (2)	0.0395 (5)
O1	−0.2966 (5)	0.7398 (2)	1.3223 (2)	0.0595 (6)
O2	0.3528 (6)	0.5462 (3)	1.1138 (2)	0.0757 (8)
Br1	0.35286 (6)	0.80290 (3)	0.58804 (2)	0.04632 (13)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0412 (14)	0.0477 (14)	0.0338 (13)	0.0047 (11)	−0.0012 (10)	−0.0033 (10)
C2	0.0392 (14)	0.0439 (13)	0.0276 (11)	−0.0007 (10)	0.0057 (10)	−0.0072 (9)
C3	0.0387 (14)	0.0428 (12)	0.0310 (12)	0.0059 (10)	0.0035 (10)	−0.0064 (10)
C4	0.0369 (13)	0.0405 (12)	0.0283 (11)	0.0025 (10)	0.0032 (9)	−0.0050 (9)
C5	0.0330 (13)	0.0449 (13)	0.0341 (12)	0.0037 (10)	0.0031 (10)	−0.0100 (10)
C6	0.0405 (15)	0.0523 (15)	0.0366 (14)	0.0057 (11)	0.0085 (11)	−0.0088 (11)
C7	0.0598 (18)	0.0451 (14)	0.0325 (13)	0.0098 (12)	0.0069 (12)	−0.0034 (10)
C8	0.078 (2)	0.0572 (17)	0.0349 (15)	0.0131 (15)	0.0123 (14)	0.0039 (12)
N1	0.0397 (13)	0.0504 (12)	0.0371 (12)	0.0090 (10)	−0.0002 (9)	−0.0059 (9)
N2	0.0382 (12)	0.0550 (13)	0.0359 (12)	0.0105 (10)	0.0076 (9)	−0.0074 (9)
N3	0.0417 (12)	0.0461 (11)	0.0287 (10)	0.0075 (9)	0.0083 (8)	−0.0045 (8)
O1	0.0640 (14)	0.0745 (14)	0.0354 (11)	0.0152 (11)	0.0188 (9)	−0.0049 (9)
O2	0.0976 (19)	0.0822 (16)	0.0386 (11)	0.0532 (15)	0.0185 (11)	0.0060 (10)
Br1	0.0522 (2)	0.0565 (2)	0.02805 (16)	0.00477 (12)	0.00836 (11)	−0.00472 (11)

Geometric parameters (Å, º) top

C1—N1	1.354 (3)	C6—O1	1.209 (3)
C1—C2	1.381 (4)	C6—N2	1.363 (4)
C1—H1	0.9300	C6—N3	1.433 (3)
C2—C3	1.398 (4)	C7—O2	1.193 (4)
C2—Br1	1.894 (2)	C7—N3	1.409 (4)
C3—C4	1.379 (3)	C7—C8	1.486 (4)
C3—H3	0.9300	C8—H8A	0.9600
C4—C5	1.401 (4)	C8—H8B	0.9600
C4—N3	1.406 (3)	C8—H8C	0.9600
C5—N1	1.319 (3)	N2—H2	0.8600
C5—N2	1.374 (3)

N1—C1—C2	122.6 (2)	N2—C6—N3	105.9 (2)
N1—C1—H1	118.7	O2—C7—N3	118.5 (2)
C2—C1—H1	118.7	O2—C7—C8	123.7 (3)
C1—C2—C3	122.0 (2)	N3—C7—C8	117.8 (2)
C1—C2—Br1	118.30 (19)	C7—C8—H8A	109.5
C3—C2—Br1	119.66 (19)	C7—C8—H8B	109.5
C4—C3—C2	115.1 (2)	H8A—C8—H8B	109.5
C4—C3—H3	122.5	C7—C8—H8C	109.5
C2—C3—H3	122.5	H8A—C8—H8C	109.5
C3—C4—C5	119.2 (2)	H8B—C8—H8C	109.5
C3—C4—N3	134.3 (2)	C5—N1—C1	115.0 (2)
C5—C4—N3	106.5 (2)	C6—N2—C5	110.9 (2)
N1—C5—N2	125.6 (2)	C6—N2—H2	124.6
N1—C5—C4	126.0 (2)	C5—N2—H2	124.6
N2—C5—C4	108.4 (2)	C4—N3—C7	124.2 (2)
O1—C6—N2	127.0 (3)	C4—N3—C6	108.4 (2)
O1—C6—N3	127.1 (3)	C7—N3—C6	127.4 (2)

N1—C1—C2—C3	−0.5 (5)	N1—C5—N2—C6	−178.9 (3)
N1—C1—C2—Br1	179.6 (2)	C4—C5—N2—C6	0.7 (3)
C1—C2—C3—C4	0.1 (4)	C3—C4—N3—C7	0.3 (5)
Br1—C2—C3—C4	−179.98 (19)	C5—C4—N3—C7	−179.4 (3)
C2—C3—C4—C5	0.5 (4)	C3—C4—N3—C6	−179.8 (3)
C2—C3—C4—N3	−179.2 (3)	C5—C4—N3—C6	0.5 (3)
C3—C4—C5—N1	−0.8 (4)	O2—C7—N3—C4	2.8 (5)
N3—C4—C5—N1	178.9 (3)	C8—C7—N3—C4	−177.5 (3)
C3—C4—C5—N2	179.5 (2)	O2—C7—N3—C6	−177.1 (3)
N3—C4—C5—N2	−0.7 (3)	C8—C7—N3—C6	2.6 (5)
N2—C5—N1—C1	−179.9 (3)	O1—C6—N3—C4	−179.6 (3)
C4—C5—N1—C1	0.5 (4)	N2—C6—N3—C4	0.0 (3)
C2—C1—N1—C5	0.2 (4)	O1—C6—N3—C7	0.3 (5)
O1—C6—N2—C5	179.1 (3)	N2—C6—N3—C7	179.8 (3)
N3—C6—N2—C5	−0.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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.

Experimental details

Crystal data
Chemical formula	C₈H₆BrN₃O₂
M_r	256.07
Crystal system, space group	Triclinic, 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)
V (Å³)	450.8 (2)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.53
Crystal size (mm)	0.41 × 0.16 × 0.11

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.423, 0.607
No. of measured, independent and observed [I > 2σ(I)] reflections	2559, 1685, 1583
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.074, 1.07
No. of reflections	1685
No. of parameters	128
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	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···A	D—H	H···A	D···A	D—H···A
N2—H2···N1ⁱ	0.86	2.02	2.877 (3)	174.5
C3—H3···O2ⁱⁱ	0.93	2.56	3.481 (3)	171.8

Symmetry codes: (i) −x−1, −y+2, −z+2; (ii) −x+1, −y+1, −z+2.

References

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