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

In the title quinazoline derivative, C21H17N3O2, the benzimidazole unit makes dihedral angles of 8.29 (5) and 81.79 (5)° with the benzene rings of the quinazoline and methoxyphenol units, respectively. The nitrogen-containing six-membered ring adopts a half-chair conformation. In the crystal, the molecules are linked through O—H⋯N hydrogen bonds into screw chains along the b axis; adjacent chains are further connected by N—H⋯O hydrogen bonds, thereby forming a two-dimensional network lying parallel to the bc plane. Weak C—H⋯π and π⋯π interactions with centroid–centroid distances of 3.5258 (8) and 3.7184 (7) Å are present and N⋯O [2.6816 (15) and 3.0519 (15) Å] short contacts also occur.


Experimental
The title compound was synthesized by adding 2-hydroxy-4-methoxybenzaldehyde (0.304 g, 2.0 mmol) to a solution of 2-(2-aminophenyl)-1H-benzimidazole (0.418 g, 2.0 mmol) in ethanol (30 mL). The mixture was refluxed with stirring for 2 hrs. The color of the resulting solution was pale-yellow. Pale-yellow blocks were formed after three weeks of slow evaporation of ethanol at room temperature.

Refinement
H atom attached to O1 and N3 were located in a difference maps and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.95 Å for aromatic and CH; and 0.98 Å for CH 3 . The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. The highest residual electron density peak is located at 0.67 Å from C13 and the deepest hole is located at 0.45 Å from C14. Fig. 1. The molecular structure of the title compound, with 50% probability displacement ellipsoids.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 120.0 (1) K.
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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.