3-{5-Ethoxycarbonyl-1-[3-(2-oxopyrrolidin-1-yl)propyl]-1H-benzimidazol-2-yl}benzoic acid

In the title compound, C24H25N3O5, the ethoxy group is disordered over two orientations in a 0.853 (14):0.147 (14) ratio. The benzimadazole ring system (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 35.47 (7)° with the attached benzene ring. The pyrrolidine ring adopts an envelope conformation with a methylene C atom as the flap. In the crystal, inversion dimers linked by pairs of O—H⋯N hydrogen bonds generate R 2 2(16) loops. C—H⋯O interactions link the dimers into a three-dimensional network.

In the title compound, C 24 H 25 N 3 O 5 , the ethoxy group is disordered over two orientations in a 0.853 (14):0.147 (14) ratio. The benzimadazole ring system (r.m.s. deviation = 0.016 Å ) makes a dihedral angle of 35.47 (7) with the attached benzene ring. The pyrrolidine ring adopts an envelope conformation with a methylene C atom as the flap. In the crystal, inversion dimers linked by pairs of O-HÁ Á ÁN hydrogen bonds generate R 2 2 (16) loops. C-HÁ Á ÁO interactions link the dimers into a three-dimensional network.
The ethoxy group is disordered over two position with the final refined occupancies of 0.853 (14) In the crystal (Fig. 2), O-H···N and C-H···O interactions (Table 1) link the molecules into a three-dimensional network.

Experimental
Ethyl 3-amino-4-(3(2-oxopyrrolidin-1yl)propylamino)benzoate (0.84 mmol) and sodium metabisulfite adduct of 4-carboxy benzaldehyde (1.68 mmol) were dissolved in DMF. The reaction mixture was reflux at 130 °C for 2 hrs. After completion, the reaction mixture was diluted in Ethyl acetate (20 ml) and washed with water (20 ml). The organic layer was collected, dried over Na 2 SO 4 and the evaporated in vacuo to yield the product. The product was recrystallized from ethyl acetate as brown plates.

Refinement
O bound H atoms were located from a difference Fourier maps and freely refined. The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-0.99 Å and U iso (H) = 1.2U eq (C) and 1.5U eq (C-methyl). The ethoxy group disordered over two postion with the final refine occupancies 0.853 (14):0.147 (14).
A rigid bond and similar restraint were applied for the disordered component. The same anisotropic displacement are used for the C23X and C24X.  The structure of the title compound, showing 50% probability displacement ellipsoids.    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.