2-(2-Methyl-5-nitro-1H-imidazol-1-yl)ethyl 2-bromobenzoate

In the title compound, C13H12BrN3O4, the dihedral angle between the benzene and imidazole rings is 30.6 (2)°. In the crystal, molecules are linked into chains parallel to [001] by C—H⋯O hydrogen bonds. The crystal packing is further consolidated by π–π interactions [centroid–centroid distance = 3.482 (2) Å].

In the title compound, C 13 H 12 BrN 3 O 4 , the dihedral angle between the benzene and imidazole rings is 30.6 (2) . In the crystal, molecules are linked into chains parallel to [001] by C-HÁ Á ÁO hydrogen bonds. The crystal packing is further consolidated byinteractions [centroid-centroid distance = 3.482 (2) Å ].

Related literature
For background information and the crystal structure of the 4flouro analogue of the title compound, see: Yousuf et al. (2012).  Table 1 Hydrogen-bond geometry (Å , ).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2520). The title compound is an ester derivative of a broad spectrum antibiotic, metronidazole, commonly known as flagyl. In continuation of our research (Yousuf et al., 2012) we have now synthesized the title compound to evaluate its antiglycation potential. In this article, we report the synthesis and crystal structure of the title compound.

Experimental
The synthesis of the title compounds was acheived by reacting metronidazole (171 mg, 1.0 mmole) with 2-bromobenzoic acid (1.2 equiv.) in the presence of dicyclohexylcarbodiimide (245 mg, 1.2 mmole) and 4-dimethylaminopyridine (0.35 mmole) in dichloromethane (10 ml) at room temperature for 40-45 h. The progress of the reaction was monitored by TLC. The reaction was quenched with 20 ml HCl (0.5 M) and then basified with sat. NaHCO 3 . It was extracted with dichloromethane and evaporated in vaccuo to obtain a crude product. The crude product was purified by using silica gel chromatography (EtOAc: hexane, 3.0: 7.0 to 7.0: 3.0) which afforded the title compound in 85% yield. Recrystallization by the slow evaporation of a dichloromethane solution of the title compound afforded pure crystals found suitable for single-crystal X-ray diffraction studies. All chemicals were purchased from Sigma-Aldrich.

Refinement
H atoms on methyl, methylene and methine were positioned geometrically with C-H = 0.96, 0.97 and 0.93 Å respectively, and constrained to ride on their parent atoms with U iso (H)= 1.2U eq (CH and CH 2 ) and 1.5U eq (CH 3 ). A rotating group model was applied to the methyl groups.

Figure 2
A view of the C--H···O hydrogen bonds (dotted lines) in the crystal structure of the title compound. H atoms nonparticipating in hydrogen-bonding were omitted for clarity.

2-(2-Methyl-5-nitro-1H-imidazol-1-yl)ethyl 2-bromobenzoate
Crystal data 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 > σ(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.