Ethyl 6-methyl-2-oxo-4-[4-(1H-tetrazol-5-yl)phenyl]-1,2,3,4-tetrahydropyrimidine-5-carboxylate–dimethylformamide–water (2/1/1)

The asymmetric unit of the title compound, 2C15H16N6O3·C3H7NO·H2O, contains two independent ethyl 6-methyl-2-oxo-4-[4-(1H-tetrazol-5-yl)phenyl]-1,2,3,4-tetrahydropyrimidine-5-carboxylate molecules, in which the dihedral angles between the tetrazole and benzene rings are 20.54 (12) and 12.13 (12)°. An intramolecular C—H⋯O hydrogen bond occurs in each molecule. In the crystal, N—H⋯O, N—H⋯N, O—H⋯O and O—H⋯N hydrogen bonds, as well as weak C—H⋯O and C—H⋯N hydrogen bonds, link the molecules into a three-dimensional supramolecular architecture. π–π stacking is also observed between parallel tetrazole rings of adjacent molecules, the centroid–centroid distance being 3.482 (6) Å.


Comment
3,4-Dihydropyimidin-2(1H)-ones have shown good drug activity (Atwal et al., 1990;Kappe & Stadler, 2004). The tetrazoles have been showed that analogs of biologically active carboxylic acids in which the carboxyl group is replaced by a 5-tetrazolyl group might interfere with the normal utilization of the respective carboxylic acids. The Biginelli derivative was obtained from p-cyanobenzaldehyde, that was used to yield tetrazole derivative. Here we report the synthesis and crystal structure of the title compound ( Fig. 1).
The bond distances and bond angles in the title compound agree very well with the corresponding distances and angles reported for a closely related compound. There are two biginelli derivatives and two solvate molecules in an asymmetric unit. The inter-molecular N-H···O and C-H···O hydrogen bonds link the compound to two-dimensional structure (Table   1), in which they may be effective in the stabilization of the structure. π-π contact between the tetrazole rings, Cg1-Cg1 i [symmetry code: (i) -x, 1-y, -z, where Cg1 and Cg1 i are centroids of the rings (N2-C15)] may further stabilize the structure, centroid-centroid distance of 3.482 (6) Å.

Experimental
Cyanobenzaldehyd and ethyl acetoacetate and urea (1:1:1) was added to round-bottom flask without solvent under nitrogen. The temperature was raised to 80°C in one hour gradually and the mixture was stirred at this temperature for 12 h.
The system was treated with 30 ml of ethanol 95% and cooled. The precipitate was filtered and washed with a small amount of ethanol 95%. The above-mentioned compound (10 mmol) was added to sodium azide (15 mmol) and ammonia chloride (12 mmol) with DMF solvent. The temperature was raised to 115°C in one hour gradually and the mixture was stirred at this temperature for 36 h. The system was treated with 30 ml of water and cooled. The precipitate was filtered at pH 3. Single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of a solution of the title compound in DMF/water at room temperature

Refinement
H-atoms bonded to the C-atoms were positioned geometrically and refined using a riding model with C-H = 0.93-1.00 Å and U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for the others. H-atoms bonded to the N-atoms and O-atom were located from a difference Fourier map and refined in riding mode with O-H = 0.85 and N-H 0.86 Å, U iso (H) = 1.5U eq (O) and 1.2U eq (N).

Figure 1
Perspective structure of the title compound, showing the atom-numbering scheme.  The crystal packing of the title compound viewed along the a axis showing the hydrogen bondings network.

Ethyl 6-methyl-2-oxo-4-[4-(1H-tetrazol-5-yl)phenyl]-1,2,3,4-tetrahydropyrimidine-5-carboxylate-
where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.011 Δρ max = 0.38 e Å −3 Δρ min = −0.29 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 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.  (10) (17)  Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x+1, −y, −z+1; (iii) x, y, z−1; (iv) x+1, y−1, z+1.