Crystal structure of ethyl 2-[2-(4-methylbenzoyl)-5-p-tolyl-1H-imidazol-1-yl]acetate

The crystal structure of ethyl 2-[2-(4-methylbenzoyl)-5-p-tolyl-1H-imidazol-1-yl]acetate is stabilized by intermolecular C—H⋯N and C—H⋯O interactions.


Chemical context
Imidazole and its derivatives have numerous pharmaceutical applications including uses as antifungal (Shingalapur et al. 2009), antimicrobial (Sharma et al. 2009), anti-inflammatory (Puratchikody et al. 2007), analgesic (Achar et al. 2010), antitubercular (Pandey et al. 2009), antidepressant (Hadizadeh et al. 2008, antileishmanial (Bhandari et al. 2009) and anticancer agents (Ozkay et al. 2010). We are interested in the synthesis of active pharmaceutical ingredients (APIs) based on imidazoles and we report here the synthesis and crystal structure of the title imidazole derivative.

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. The C-N bond lengths within the imidazole ring are 1.373 (3) Å (C10-N2), 1.372 (3) Å (C8-N2), 1.349 (3) Å (C9-N1) and 1.329 (3) Å (C10-N1). These bond distances are shorter than the single-bond length (1.443 Å ) and longer than the accepted double-bond length (1.269 Å ) due to electron delocalization in the central imidazole ring. The phenyl rings and the plane of the imidazole ring are inclined at angles of 45.4 (1) (with the C12-C17 ring) and 52.5 (1) (with the C2-C7 ring). The phenyl rings are oriented to each other with a dihedral angle of 88.1 (1) . Further, the imidazole ring is inclined at an angle of 85.2 (2) to the best-fit plane through atoms C19, C20, O3, C21 and C22 of the ethyl acetate substituent. The molecular structure is also influenced by the formation of an intramolecular C6-H6Á Á ÁO2 hydrogen bond, Table 1, which generates an S(8) ring motif (Bernstein et al., 1995).

Supramolecular features
The N-bound methylene group of the side chain is connected with the carbonyl oxygen of an adjacent molecule through a C19-H19AÁ Á ÁO2 hydrogen bond, forming a linear C(5) chain motif along the a axis, Table 1

Synthesis and crystallization
The title compound was synthesized from a mixture of 2-(4methoxyphenyl)-2-oxoacetaldehyde (1 mmol), glycine methyl ester hydrochloride (1 mmol) and selenium dioxide (1 mmol) in a basic environment in acetonitrile at 373 K. Crystals suitable for X-ray investigation were obtained by solvent evaporation from the resulting solution in 33% yield. The molecular structure of the title compound, showing the atomnumbering scheme and 50% probability displacement ellipsoids. The methyl group (C22) of the side chain is disordered over two positions each with 0.5 occupancy.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93 À0.97 Å and U iso (H) = 1.2-1.5U eq (parent C atom). The methyl group C22 of the side chain is disordered over two positions, each with a site-occupancy factor of 0.5. The atomic displacement parameters of these two C atoms are restrained to be equivalent and the C21-C22 and C21-C22 0 bond distances were restrained during the refinement using DFIX commands.  Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL/PC (Sheldrick, 2008) and PLATON (Spek, 2009