4-(5,6-Dihydro­benzimidazo[1,2-c]quinazolin-6-yl)benzene-1,3-diol dimethyl sulfoxide monosolvate

Naser Eltaher Eltayeb; Siang Guan Teoh; Chin Sing Yeap; Hoong-Kun Fun

doi:10.1107/S160053681102304X

. 2011 Jun 18;67(Pt 7):o1721–o1722. doi: 10.1107/S160053681102304X

4-(5,6-Dihydrobenzimidazo[1,2-c]quinazolin-6-yl)benzene-1,3-diol dimethyl sulfoxide monosolvate

Naser Eltaher Eltayeb ^a,^b, Siang Guan Teoh ^a, Chin Sing Yeap ^c,^‡, Hoong-Kun Fun ^c,^*,^§

PMCID: PMC3152048 PMID: 21837112

Abstract

In the title solvated benzimidazole compound, C₂₀H₁₅N₃O₂·C₂H₆OS, both the benzimidazole fused-ring system and the complete dimethyl sulfoxide solvent molecule are disordered over two sets of sites, in 0.750 (5):0.250 (5) and 0.882 (4):0.118 (4) ratios, respectively. The conformation of the pyrimidine ring is close to a half-chair for the major disorder component, whereas for the minor component it is close to a boat. The dihydroxyphenyl ring is almost perpendicular to the mean plane of the benzimidazole ring [dihedral angle = 87.3 (2)° for the major disorder component and 88.3 (5)° for the minor disorder component]. In the crystal, molecules are linked into layers parallel to (110) by O—H⋯N and C—H⋯O hydrogen bonds. A bifurcated O—H⋯(O,S) bond links the benzimidazole and solvent molecules.

Related literature

For related structures and background to benzimidazoles, see: Eltayeb et al. (2007a ▶,b ▶,c ▶, 2009 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶). For ring conformations, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C₂₀H₁₅N₃O₂·C₂H₆OS
M _r = 407.48
Orthorhombic,
a = 9.9310 (18) Å
b = 16.342 (3) Å
c = 23.516 (5) Å
V = 3816.5 (13) Å³
Z = 8
Mo Kα radiation
μ = 0.20 mm⁻¹
T = 100 K
0.33 × 0.28 × 0.27 mm

Data collection

Bruker APEXII DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.937, T _max = 0.949
22793 measured reflections
3345 independent reflections
3118 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.096
wR(F ²) = 0.208
S = 1.28
3345 reflections
348 parameters
514 restraints
H-atom parameters constrained
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.37 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/S160053681102304X/hb5886sup1.cif

e-67-o1721-sup1.cif^{(30.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681102304X/hb5886Isup2.hkl

e-67-o1721-Isup2.hkl^{(164.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681102304X/hb5886Isup3.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
O1—H1O1⋯S1A	0.94	2.82	3.732 (3)	163
O1—H1O1⋯O3A	0.94	1.71	2.619 (9)	163
O2—H1O2⋯N2Aⁱ	0.88	1.95	2.739 (6)	150
C11A—H11A⋯O2ⁱⁱ	0.93	2.40	3.329 (9)	174

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

NEE and SGT thank the Malaysian Government and Universiti Sains Malaysia (USM) for the RU research grant 1001/PKIMIA/815067. NEE also thanks USM for a post-doctoral fellowship and the International University of Africa (Sudan) for providing study leave. HKF and CSY thank USM for the Research University Grant 1001/PFIZIK/811160.

supplementary crystallographic information

Comment

As part of our ongoing structural studies of benzimidazoles (Eltayeb et al., 2007a,b,c, 2009) we now describe in this paper the single-crystal X-ray diffraction study of title compound, (I), (Fig. 1). Furthermore, this paper describes for the first time a simple method for synthesis of benzimidazo[1,2-c]quinazoline derivatives using zinc chloride as a homogenous catalyst, herein, and thereafter to be called the "Taha-Teoh's method".

The benzimidazole fused ring system in (I) is disordered over two sets of sites with refined site occupancies of 0.750 (5) and 0.250 (5). The solvent molecule is also disordered over two orientations with refined site occupancies of 0.882 (4) and 0.118 (4). The conformation for pyrimidine ring is close to a half-chair conformation for major component whereas for minor component it is close to a boat conformation (Cremer & Pople, 1975). The dihydroxyphenyl ring is almost perpendicular to the mean plane of benzimidazole ring (N1A/C1A–C6A/N2A/C7A) with the dihedral angle of 87.3 (2)° whereas this angle is 88.3 (5)° for minor component. In the crystal structure, the molecules are linked into infinite one-dimensional chains along a axis by intermolecular O2—H1O2···N2A hydrogen bonds and the intermolecular C11A—H11A···O2 hydrogen bonds (Table 1) further linked these chains into planes parallel to ab plane (Fig. 3). The benzimidazole molecule and the solvent molecule is stabilized by the O1—H1O1···S1A and O1—H1O1···O3A interactions (Table 1).

Experimental

To a solution of 2-(2-aminophenyl)-1H-benzimidazole (0.209 g, 1.0 mmol) in ethanol (30 ml) was added 2,4-dihydroxybenzaldehyde (0.138 g, 1.0 mmol). The color of the resulting solution is pale-pink. Then on adding zinc chloride (0.136 g, 1.0 mmol), the color of solution changed to yellowish-pink. The mixture was refluxed with stirring for 3 hours. The product (yellow precipitate) was obtained by evaporation of the solvent under reduced pressure using a rotary evaporator. Yellow blocks of (I) were formed after several days of slow evaporation of an acetone solution layered with a small amount of dimethylsulfoxide at room temperature.