2-(5,6-Dihydro­benzimidazo[1,2-c]quinazolin-6-yl)-5-methyl­phenol

Naser Eltaher Eltayeb; Siang Guan Teoh; Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536811032673

. 2011 Aug 27;67(Pt 9):o2373–o2374. doi: 10.1107/S1600536811032673

2-(5,6-Dihydrobenzimidazo[1,2-c]quinazolin-6-yl)-5-methylphenol

Naser Eltaher Eltayeb ^a,^b, Siang Guan Teoh ^a, Madhukar Hemamalini ^c, Hoong-Kun Fun ^c,^*,^‡

PMCID: PMC3200579 PMID: 22058979

Abstract

In the title compound, C₂₁H₁₇N₃O, the imidazole ring is essentially planar, with a maximum deviation of 0.009 (1) Å. The molecule is disordered over two sites corresponding to a rotation of approximately 180° with a refined occupancy ratio of 0.9180 (14):0.0820 (14). The central pyrimidine ring makes dihedral angles of 5.02 (5), 3.97 (5) and 6.28 (5)°, respectively, with the planes of the imidazole and the terminal phenyl rings for the major component; the values for the minor component are 5.8 (7), 5.0 (6) and 8.5 (6)°, respectively. Part of the observed planarity is accounted for in terms of an intramolecular N—H⋯O hydrogen bond. In the crystal, molecules of the major component are connected by O—H⋯N hydrogen bonds, forming supramolecular chains along the c axis.

Related literature

For applications of benzimidazoles, see: Sun et al. (2010 ▶); Harrell et al. (2004 ▶). For related structures, see: Eltayeb et al. (2007 ▶, 2009 ▶, 2011 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₁H₁₇N₃O
M _r = 327.38
Monoclinic,
a = 15.1292 (3) Å
b = 12.2648 (2) Å
c = 17.1909 (3) Å
β = 96.233 (1)°
V = 3171.03 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.59 × 0.21 × 0.20 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.951, T _max = 0.983
24277 measured reflections
6164 independent reflections
4808 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.126
S = 1.04
6164 reflections
296 parameters
44 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.41 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811032673/tk2779sup1.cif

e-67-o2373-sup1.cif^{(28.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811032673/tk2779Isup2.hkl

e-67-o2373-Isup2.hkl^{(295.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811032673/tk2779Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H1N3⋯O1	0.90	2.39	2.9655 (11)	123
O1—H1O1⋯N2ⁱ	0.919 (16)	1.830 (16)	2.7038 (10)	158.0 (15)

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Symmetry code: (i) Inline graphic .

Acknowledgments

NEE and SGT thank the Malaysian Government and Universiti Sains Malaysia for the RU research grant (1001/PKIMIA/815067). NEE also thanks Universiti Sains Malaysia for a post-doctoral fellowship and the International University of Africa (Sudan) for providing study leave. HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160. MH also thanks the Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Benzimidazoles are known to be strong chelating agents coordinating through both the C═N N atoms (Sun et al., 2010). The benzimidazole ring system is present in the clinically approved anthelmintics, anti-ulcer, anti-viral, and anti-histamine drugs (Harrell et al., 2004). As part of our on-going structural studies of benzimidazoles (Eltayeb et al., 2007, 2009, 2011), we now describe in this paper the single-crystal X-ray diffraction study of title compound (I).

The molecular structure of (I) is shown in Fig. 1. The 2-(5,6 dihydrobenzimidazo[1,2-c]quinazolin-6-yl) molecule is disordered over two sites corresponding to a rotation of approximately 180\% with a refined occupancy ratio of 0.9180 (14):0.0820 (14). The imidazole (N1/N2/C6/C7/C8) ring is essentially planar, with a maximum deviation of 0.009 (1) Å for atom C7. The central pyrimidine ring makes dihedral angles of 5.02 (5), 3.97 (5), 6.28 (5) ° for the major component, and 5.8 (7), 5.0 (6) and 8.5 (6) ° for the minor component, respectively, with the plane of the imidazole and with those through the terminal phenyl rings.

In the crystal structure (Fig. 2), the molecules of the major component are connected by O1—H1O1···N2 hydrogen bonds (Table 1) forming a supramolecular chain along the c-axis.

Experimental

To a solution of 2-(2-aminophenyl)-1H-benzimidazole (0.418 g, 2.0 mmol) in ethanol (30 mL) was added 2-hydroxy-4-methylbenzaldehyde (0.272 g, 2.0 mmol). The mixture was refluxed with stirring for two hours after which the colour of the resulting solution turned pale-yellow. Colourless crystals were formed after several days of slow evaporation of its ethanol solution held at room temperature.