Ethyl 7-(2-chlorophenyl)-5-trifluoromethyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxylate

In the title compound, C15H12ClF3N4O2, the dihydropyrimidine ring exhibits an envelope conformation. The dihedral angle between the mean planes of the dihydropyrimidine and phenyl rings is 83.94 (6)°. The OCH2CH3 group is disordered over two sites with occupancies of 0.155 (3) and 0.845 (3). The crystal packing is stabilized by intermolecular N—H⋯N hydrogen bonds.

In the title compound, C 15 H 12 ClF 3 N 4 O 2 , the dihydropyrimidine ring exhibits an envelope conformation. The dihedral angle between the mean planes of the dihydropyrimidine and phenyl rings is 83.94 (6) . The OCH 2 CH 3 group is disordered over two sites with occupancies of 0.155 (3) and 0.845 (3). The crystal packing is stabilized by intermolecular N-HÁ Á ÁN hydrogen bonds.

Related literature
For the anticancer activity, inhibition of the MDM2-p53 protein-protein interaction and the antituberculosis and dehydrogenase inhibitory activity of [1,2,4] Table 1 Hydrogen-bond geometry (Å , ).   (Gujjar et al., 2009). Therefore, the preparation or structural modification of these nitrogen-containing heterocyclic scaffolds is of considerable interest for both organic and medicinal chemistry. The introduction of a trifluoromethyl group into organic molecules often changes their physical, chemical, and physiological properties (Kirk, 2006). During the synthesis of trifluoromethylated 1,2,4-Triazolo[1,5-a]pyrimidine derivatives, the title compound (I) was isolated and its structure was determined by X-ray analysis. The results are presented here.

Experimental
The title compound was synthesized according the procedure reported by Pryadeina et al. (2004). A mixture of 0.01 mol of ethyl 4,4,4-trifluoro-3-oxobutanoate, 0.01 mol of 2-chlorobenzaldehyde and 0.01 mol of 1H-1,2,4-triazol-5-amine in 20 mL of ethanol containing a catalytic amount of hydrochloric acid was heated for 12 h under reflux. Then the solvent was removed under reduced pressure. The residue was added to a solution of p-toluenesulfonic acid, 0.05 g, in 100 mL of benzene, and the mixture was heated for 8 h with simultaneous removal of water as azeotrope with benzene. The solution was filtered while hot, the filtrate was evaporated, and the precipitate was recrystallized from ethanol. Cooling the ethanol solution slowly gave single crystals suitable for X-ray diffraction.

Refinement
The H atoms bound to N atoms were located in a difference map and were refined freely [refined N-H length, 0.90 (2)Å].
All other H atoms were placed in calculated positions, with C-H = 0.95, 0.98, 0.99 or 1.00 Å, and included in the final cycles of refinement using a riding model, with U iso (H) = 1.2U eq (parent atom). The OCH 2 CH 3 group is disordered over two sites with occupancies of 0.155 (3) and 0.845 (3). The atom pairs of C12 and C12', C13 and C13', and O2 and O2' are constrained supplementary materials sup-2 to have the same anisotropic displacement parameters. The bond lengths of ethyl group of C12-C13 and C12'-C13' is restrained to 1.54Å with esd of 0.01Å. The distance between O2 and C12, O2' and C12' is restrained to 1.42Å with esd of 0.01Å. The atoms of O2 and O2' are restrained to be at the distance of 1.38Å from the atom of C11 with esd of 0.01Å. Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme. The minor part of the disordered moieties were omitted for clarity. Ethyl 7-(2-chlorophenyl)-5-trifluoromethyl-4,7-dihydro-1,2,4-triazolo[1,5-\ a]pyrimidine-6-carboxylate

Special details
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.