Ethyl 2-(4-methoxyphenyl)-1-[3-(2-oxopyrrolidin-1-yl)propyl]-1H-benzimidazole-5-carboxylate

The asymmetric unit of the title compound, C24H27N3O4, contains two molecules, A and B. The benzimidazole rings are essentially planar [maximum deviations = 0.0144 (10) and 0.0311 (8) Å in A and B, respectively]. The dihedral angle between the benzimidazole mean plane and its attached benzene ring is 36.90 (5) ° for molecule A and 51.40 (5) ° for molecule B. In both molecules, the pyrrolidine ring adopts an envelope conformation with a C atom as the flap. In molecule B, the flap C atom is disordered over two positions in a 0.711 (6):0.289 (6) ratio. In the crystal, C—H⋯O interactions link the molecules, generating [100] chains. The crystal packing also features weak π–π interactions between the imidazole and benzene rings [centroid–centroid distances = 3.8007 (7) and 3.8086 (7) Å] and between the benzene rings [centroid–centroid distance = 3.7001 (7) Å] and C—H⋯π interactions involving the benzene rings.

The asymmetric unit of the title compound, C 24 H 27 N 3 O 4 , contains two molecules, A and B. The benzimidazole rings are essentially planar [maximum deviations = 0.0144 (10) and 0.0311 (8) Å in A and B, respectively]. The dihedral angle between the benzimidazole mean plane and its attached benzene ring is 36.90 (5) for molecule A and 51.40 (5) for molecule B. In both molecules, the pyrrolidine ring adopts an envelope conformation with a C atom as the flap. In molecule B, the flap C atom is disordered over two positions in a 0.711 (6):0.289 (6) ratio. In the crystal, C-HÁ Á ÁO interactions link the molecules, generating [100] chains. The crystal packing also features weakinteractions between the imidazole and benzene rings [centroid-centroid distances = 3.8007 (7) and 3.8086 (7) Å ] and between the benzene rings [centroid-centroid distance = 3.7001 (7) Å ] and C-HÁ Á Á interactions involving the benzene rings.

Experimental
Ethyl 3-amino-4-(3(2-oxopyrrolidin-1yl)propylamino)benzoate (0.84 mmol) and sodium metabisulfite adduct of 4-methoxybenzaldehyde (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 recrystallised from ethyl acetate to form yellow plates.

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 100.0 (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.