Diethyl 2,6-dimethyl-4-[4-(3-phenylacryloyloxy)phenyl]-1,4-dihydropyridine-3,5-dicarboxylate hemihydrate

In the title ester derivative, C28H29NO6·0.5H2O, the 1,4-dihydropyridine ring has a flattened boat conformation. The mean plane is almost perpendicular to the attached benzene ring, making a dihedral angle of 86.87 (9)°. The terminal phenyl ring is inclined to the central benzene ring by 67.56 (12)°. In the crystal, molecules are bridged via O—H⋯O hydrogen bonds involving the partially occupied water molecule, and this arrangement is strengthened by a pair of N—H⋯O hydrogen bonds and C—H⋯O interactions. The ethyl atoms of one of the ethyl ester groups are disordered over two sites with an occupancy ratio of 0.716 (5):0.284 (5).

In the title ester derivative, C 28 H 29 NO 6 Á0.5H 2 O, the 1,4dihydropyridine ring has a flattened boat conformation. The mean plane is almost perpendicular to the attached benzene ring, making a dihedral angle of 86.87 (9) . The terminal phenyl ring is inclined to the central benzene ring by 67.56 (12) . In the crystal, molecules are bridged via O-HÁ Á ÁO hydrogen bonds involving the partially occupied water molecule, and this arrangement is strengthened by a pair of N-HÁ Á ÁO hydrogen bonds and C-HÁ Á ÁO interactions. The ethyl atoms of one of the ethyl ester groups are disordered over two sites with an occupancy ratio of 0.716 (5):0.284 (5).   Table 1 Hydrogen-bond geometry (Å , ). title compound was synthesized and we report herein on its crystal structure.
In the crystal, molecules are linked via O-H···O hydrogen bonds involving the water molecule, and this arrangement is strengthened by a pair of N-H···O hydrogen bonds and C-H···O interactions ( Fig. 2 and Table 1).

Experimental
A mixture of 3-phenyl-acrylic acid 4-formyl-phenyl ester (0.01 mol), ethyl acetoacetate (0.02 mol), and ammonium acetate (0.03 mol) in ethanol (30 ml) was refluxed for 8 h. After the reaction had completed, the mixture was quenched with an excess of water. The solid precipitated which separated was dried and recrystallized from ethanol, giving colourless block-like crystals.

Refinement
The CH 3 -CH 2 -atoms of one of the ethylester groups (C27 and C28) are disordered over two sites with an occupancy ratio of 0.716 (5):0.284 (5). The NH H atom was located in a difference Fourier map and refined with U iso (H) = 1.2U eq (N). The C-bound H atoms were positioned geometrically and constrained to ride on their parent atom: C-H = 0.93, 0.98, 0.97 and 0.96 Å for aromatic, methine, methylene and methyl H atoms, respectively, with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1.2U eq (C) for other H atoms. An isolated half water molecule (O1W) was refined isotropically with an occupancy of 0.5.

Computing details
Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles 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.

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