Ethyl 1-[2-(morpholin-4-yl)ethyl]-2-[4-(trifluoromethyl)phenyl]-1H-benzimidazole-5-carboxylate

In the title compound, C23H24F3N3O3, the morpholine ring adopts a chair conformation. The benzimidazole ring is approximately planar, with a maximum deviation of 0.028 (1) Å for one of the unsubstituted C atoms. The benzimidazole ring makes dihedral angles of 35.66 (4) and 75.45 (5)° with the attached phenyl and morpholine rings, respectively. In the crystal structure, adjacent molecules are linked via C—H⋯F and C—H⋯O hydrogen bonds to form a two-dimensional network.

In the title compound, C 23 H 24 F 3 N 3 O 3 , the morpholine ring adopts a chair conformation. The benzimidazole ring is approximately planar, with a maximum deviation of 0.028 (1) Å for one of the unsubstituted C atoms. The benzimidazole ring makes dihedral angles of 35.66 (4) and 75.45 (5) with the attached phenyl and morpholine rings, respectively. In the crystal structure, adjacent molecules are linked via C-HÁ Á ÁF and C-HÁ Á ÁO hydrogen bonds to form a two-dimensional network.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 (Boruah & Skibo, 1994). The synthesis of novel benzimidazole derivatives remains an important focus in medicinal research. Recent observations suggest that substituted benzimidazoles and heterocyclic, which are the structural isosters of nucleotides owing to their fused heterocyclic nuclei in their structures that allow them to interact easily with the biopolymers, possess potential activity with lower toxicities in the chemotherapeutic approach in man (Haugwitz, 1982;Hisano, 1982). Moreover, these fused heterocylces were distinctively studied for their antitumor, antiviral and antimicrobial activities as new nonnucleoside topoisomerase I poisons, human immunodeficiency virus-1 reverse transcriptase inhibitors and or potent DNA gyrase inhibitors (Hubschwerlen, 1992;Shi, 1996). In addition, benzimidazole derivatives have played a crucial role in the theoretical development of heterocyclic chemistry and are also used extensively in organic synthesis.

Experimental
Ethlyl-3-amino-4-(morpholinoethylamino) benzoate (0.01 mol) and sodium metabisulfite adduct of trifluromethyl benzaldehyde (0.01 mol) were dissolved in DMF. The reaction mixture was refluxed at 130°C for 4 h. 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 yield colourless blocks of (I).

Refinement
All H atoms were positioned geometrically [C-H = 0.95-0.99 Å] and were refined using a riding model, with U iso (H) = 1.2U eq (C). A rotating group model was used for the methyl group. Fig. 1. The asymmetric unit of (I), showing 30% probability displacement ellipsoids.

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.