Ethyl 4-(4-cyanophenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate

The asymmetric unit of the title compound, C15H15N3O2S, contains two independent molecules corresponding to the R and S enantiomers. The dihydropyrimidinone rings adopt a flattened boat conformation. One of the ethyl groups is disordered over two orientations with occupancy factors of 0.700 (7) and 0.300 (7). In the crystal structure, molecules are linked by intermolecular N—H⋯O hydrogen-bonding interactions into one-dimensional chains along the c-axis direction. The chains are further connected by N—H⋯S hydrogen bonds, forming a three-dimensional network.

The asymmetric unit of the title compound, C 15 H 15 N 3 O 2 S, contains two independent molecules corresponding to the R and S enantiomers. The dihydropyrimidinone rings adopt a flattened boat conformation. One of the ethyl groups is disordered over two orientations with occupancy factors of 0.700 (7) and 0.300 (7). In the crystal structure, molecules are linked by intermolecular N-HÁ Á ÁO hydrogen-bonding interactions into one-dimensional chains along the c-axis direction. The chains are further connected by N-HÁ Á ÁS hydrogen bonds, forming a three-dimensional network.
The asymmetric unit of the title compound contains two independent molecules corresponding to the R-and S-enantiomers. One ethyl group (C6-C7) is disordered over two orientations with refined occupancy factors of 0.700 (7) and 0.300 (7). The dihydropyrimidinone rings adopt a flattened boat conformation. In the crystal structure, the molecules are linked by intermolecular N-H···O hydrogen bonding interactions (Table 1) into one-dimensional chains along the c direction (Fig. 2). The chains are further connected by N-H···S hydrogen bonds forming a three-dimensional network.

Experimental
The title compound was synthesized by refluxing 4-cyanobenzaldehyde (2 mmol), ethyl acetoacetate (2 mmol), thiourea (3 mmol) and NH 4 Cl (1 mmol) in acetic acid (10 ml) at 100 °C for 8 h. The reaction mixture was then allowed to stand at room temperature and the product formed was filtered, washed with ethanol followed by water and dried. Further purification was done by recrystallization from ethanol. Single crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution for 4 weeks.

Refinement
H atoms were placed in calculated positions (N-H = 0.86 Å; C-H = 0.93-0.98 Å for Csp 2 and Csp 3 atoms, respectively), assigned fixed U iso values [U iso = 1.2Ueq(Csp 2 /N) and 1.5Ueq(Csp 3 )] and allowed to ride. The ethyl group labeled by C(6) and C(7) is disordered over two positions with occupancies of 0.700 (7) and 0.300 (7), and all disordered atoms were subjected to a rigid bond restraint.  Ethyl 4-(4-cyanophenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate  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 Rfactors(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 Occ. supplementary materials sup-9