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

In the title compound, C24H25N3O5, the benzimidazole and benzodioxole ring systems are each approximately planar [maximum deviations = 0.043 (1) and 0.036 (1) Å, respectively]. Their mean planes form a dihedral angle of 42.85 (4)°. The pyrrolidine ring has an envelope conformation with one of the methylene C atoms forming the flap. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. The crystal packing is further stabillized by weak π–π interactions between the benzene rings within the benzimidazole ring system [centroid–centroid distance = 3.7955 (7) Å]. A weak C—H⋯π interaction involving the benzodioxole ring is also present.

In the title compound, C 24 H 25 N 3 O 5 , the benzimidazole and benzodioxole ring systems are each approximately planar [maximum deviations = 0.043 (1) and 0.036 (1) Å , respectively]. Their mean planes form a dihedral angle of 42.85 (4) . The pyrrolidine ring has an envelope conformation with one of the methylene C atoms forming the flap. In the crystal, weak C-HÁ Á ÁO hydrogen bonds link the molecules into a threedimensional network. The crystal packing is further stabillized by weakinteractions between the benzene rings within the benzimidazole ring system [centroid-centroid distance = 3.7955 (7) Å ]. A weak C-HÁ Á Á interaction involving the benzodioxole ring is also present.

Experimental
Ethyl 3-amino-4-(3(2-oxopyrrolidin-1yl)propylamino)benzoate (0.84 mmol) and sodium metabisulfite adduct of piperonal (1.68 mmol) were dissolved in DMF. The reaction mixture was reflux at 403K 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.

Refinement
All the H atoms were positioned geometrically and refined using a riding-model approximation with with C-H = 0.95-0.99 Å. The U iso values were constrained to be 1.5U eq (methyl-H atom) and 1.2U eq (other H atoms). The rotating model group was applied for the methyl group.    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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1