2-(3,4-Dimethoxyphenyl)-4,5-diphenyl-1-(prop-2-en-1-yl)-1H-imidazole

In the title compound, C26H24N2O2, the planar 1H-imidazole ring makes dihedral angles of 35.78 (4), 26.35 (5) and 69.75 (5)°, respectively, with the dimethoxyphenyl ring and the phenyl rings in the 4- and 5-positions. In the crystal, C—H⋯O hydrogen bonds connect neighbouring molecules, forming infinite chains running along the b axis. Furthermore, the crystal structure exhibits a C—H-⋯π interaction between a methyl H atom and a phenyl ring from an adjacent molecule.

In the title compound, C 26 H 24 N 2 O 2 , the planar 1H-imidazole ring makes dihedral angles of 35.78 (4), 26.35 (5) and 69.75 (5) , respectively, with the dimethoxyphenyl ring and the phenyl rings in the 4-and 5-positions. In the crystal, C-HÁ Á ÁO hydrogen bonds connect neighbouring molecules, forming infinite chains running along the b axis. Furthermore, the crystal structure exhibits a C-H-Á Á Á interaction between a methyl H atom and a phenyl ring from an adjacent molecule.   Table 1 Hydrogen-bond geometry (Å , ).
In the crystal packing, molecules are linked by C-H···O hydrogen bonds, forming infinite chains running along the b axis (Table 1, Figs. 2 & 3). In addition, a C-H···π interaction is observed between the (C8)H8B methyl H atom and the C15-C20 phenyl ring of the adjacent molecule (Table 1).

Experimental
A mixture of 25 ml. of dimethyl sulfoxide and 2.4 g. (40 mmol) of potassium hydroxide was added in a 50-ml. volumetric flask equipped with a magnetic stirring bar. The mixture was stirred at room temperature for 5 minutes before adding of 3.26 g. (10 mmole) of 2-(3,4-dimethoxyphenyl)-4,5-diphenyl-1H-imidazole. Stirring was continued for 45 minutes, then 4.80 g. (20 mmol) of allylbromide was added. After being stirred for an additional 45 minutes the mixture was diluted with 20 ml. of water. The organic product was extracted with three 20-ml. portions of diethyl ether, and each ether layer was washed with three 10-ml. portions of water. The combined ether layers were dried over calcium chloride, and the solvent was removed at slightly reduced pressure. The excess allyl bromide was removed by distillation at approximately 15 mm. The residue was solidified upon cooling and scratching to furnish the title compound (3.22 g; 88%). Mono crystals suitable for X-ray analyses were obtained by slow evaporation method from ethanol at room temperature. M.p.

Refinement
Hydrogen atoms were located geometrically and refined using a riding model with C-H = 0.93-0.97 Å, and with U iso =1.2U eq (C) or 1.5U eq (C methyl ). The methyl groups were allowed to rotate but not to tip.

Figure 1
The molecular structure of (I) with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.   View of the crystal packing and hydrogen bonding of (I) down the b axis. H atoms not involved in hydrogen bonds have been omitted for clarity. Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.