Crystal structure of 5-(5,6-di­hydro­benzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-2-meth­oxy­phenol

Farook Adam; Md Azharul Arafath; A Haque Rosenani; Mohd R Razali

doi:10.1107/S2056989015021180

. 2015 Nov 21;71(Pt 12):o971–o972. doi: 10.1107/S2056989015021180

Crystal structure of 5-(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-2-methoxyphenol

Farook Adam ^a,^*, Md Azharul Arafath ^a, A Haque Rosenani ^a, Mohd R Razali ^a

PMCID: PMC4719928 PMID: 26870556

Abstract

In the molecule of the title compound, C₂₁H₁₇N₃O₂, the 5,6-dihydrobenzimidazo[1,2-c]quinazoline moiety is disordered over two orientations about a pseudo-mirror plane, with a refined occupancy ratio of 0.863 (2):0.137 (2). The dihedral angles formed by the benzimidazole ring system and the benzene ring of the quinazoline group are 14.28 (5) and 4.7 (3)° for the major and minor disorder components, respectively. An intramolecular O—H⋯O hydrogen bond is present. In the crystal, molecules are linked by O—H⋯N hydrogen bonds, forming chains running parallel to [10-1].

Keywords: crystal structure, cyclization, imidazole derivative

Related literature

For the structure of related N-heterocyclic Schiff base compounds, see: Cheng et al. (2006 ▸); Ünver et al. (2010 ▸); Gurumoorthy et al. (2010 ▸); Natarajan & Mathews (2011 ▸); Alliouche et al. (2014 ▸). graphic file with name e-71-0o971-scheme1.jpg

Experimental

Crystal data

C₂₁H₁₇N₃O₂
M _r = 343.38
Monoclinic,
a = 9.7359 (7) Å
b = 10.0822 (7) Å
c = 17.4624 (13) Å
β = 94.2958 (15)°
V = 1709.3 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 294 K
0.29 × 0.20 × 0.12 mm

Data collection

Bruker APEXII CCD diffractometer
19177 measured reflections
4987 independent reflections
3575 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.139
S = 1.05
4987 reflections
370 parameters
752 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▸); cell refinement: SAINT (Bruker, 2008 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick 2008 ▸); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2015 ▸); molecular graphics: SHELXTL (Sheldrick, 2008 ▸); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989015021180/rz5173sup1.cif

e-71-0o971-sup1.cif^{(675KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015021180/rz5173Isup2.hkl

e-71-0o971-Isup2.hkl^{(397KB, hkl)}

Click here for additional data file.^{(6.9KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015021180/rz5173Isup3.cml

Click here for additional data file.^{(1.2MB, tif)}

c . DOI: 10.1107/S2056989015021180/rz5173fig1.tif

The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level. Only the major component of the disordered 5,6-dihydrobenzimidazo[1,2-c]quinazoline moiety is shown.

Click here for additional data file.^{(1.8MB, tif)}

b c . DOI: 10.1107/S2056989015021180/rz5173fig2.tif

Crystal packing of the title compound viewed down the b axis. Intermolecular hydrogen bonds are shown as dashed lines. Only the major component of the disordered 5,6-dihydrobenzimidazo[1,2-c]quinazoline moiety is shown.

CCDC reference: 1048554

Additional supporting information: 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⋯O2	0.80 (3)	2.25 (3)	2.6706 (16)	112 (3)
O1—H1O1⋯N1ⁱ	0.80 (3)	1.98 (3)	2.703 (2)	150 (3)
O1—H1O1⋯N1X ⁱ	0.80 (3)	2.18 (3)	2.873 (9)	145 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

The research was supported financially by the RU grant 1001/PKIMIA/811269 from University Sains Malaysia. The authors wish to thank The World Academy of Science (TWAS) for a scholarship to MdAA.

supplementary crystallographic information

S1. Comment

The title compound (Fig. 1), which features a cyclic structure instead of the planned imine C═N double bond of a Schiff base compound, was unexpectedly obtained by the reaction of 3-hydroxy-4-methoxy-benzaldehyde and 2-(2-aminophenyl)-1H-benzimidazole. In the molecule, the 5,6-dihydrobenzimidazo[1,2-c]quinazoline moiety has been found to be disordered over two sets of sites, with occupancy ratio of 0.863 (2):0.137 (2), related by a pseudo-mirror plane approximately parallel to the (1 0 1) plane. Within the disordered components, the dihedral angle between the benzimidazole ring and the benzene ring of the quinazoline group is 14.28 (5) and 4.7 (3)°, respectively. The molecular conformation is enforced by an intramolecular O—H···O hydrogen bond (Table 1). In the crystal, molecules form chains parallel to the [1 0 -1] direction via O—H···N hydrogen bonds.

S2. Refinement

During the refinement of the disordered 5,6-dihydrobenzimidazo[1,2-c]quinazoline moiety DELU and SIMU restraints were applied. The phenolic hydrogen atom was located in a difference Fourier map and refined freely. All other H atoms were calculated geometrically and refined using a riding model, with C—H = 0.93-0.98 Å, N—H = 0.86 Å, and with U_iso(H) = 1.2 U_eq(C, N) or 1.5 U_eq(C) for methyl H atoms. A rotating model was used for the methyl group. Four outliers (-3 0 1, -7 0 1, 0 0 2, 0 0 6) were omitted in the last cycles of refinement.

S3. Synthesis and crystallization

3-Hydroxy-4-methoxy-benzaldehyde (5 mmol, 0.761 g) and 2-(2-aminophenyl)-1H-benzimidazole (5 mmol, 1.046 g) were dissolved in ethanol in separate beakers, then the amine solution was added drop wise with stirring to the aldehyde solution in a round bottomed flask. The mixture was refluxed over 4h. The product was filtered and washed with hot ethanol and n-hexane, then dried out over 24 h under reduced pressure in a desiccator. Single crystals suitable for X-ray analysis were formed on slow evaporation of the ethanol solution. M. p.: 560-561 K; Yield: 97%. Anal. Cal. for C₂₁H₁₇N₃O₂ (fw: 343.43 g/mol); C, 73.56; H, 4.95; N, 12.23; Found: C, 73.90; H, 4.56; N, 12.24%. IR (KBr pellets ν_max/cm^-1): 3382 ν(OH), 1616 ν(C=N), 1497 ν(CH3, stre.), 1154 ν(C—O), 1127 ν(C—N).