Diethyl 2,6-dimethyl-4-(4-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylate

In the title compound, C18H22N2O4, the dihedral angle between the two rings is 87.90 (6)°. The mean devation of the atoms in the dihydropyridine plane is 0.082 (3) Å. In the crystal, molecules are linked by intermolecular N—H⋯N hydrogen bonds, generating chains.

In the title compound, C 18 H 22 N 2 O 4 , the dihedral angle between the two rings is 87.90 (6) . The mean devation of the atoms in the dihydropyridine plane is 0.082 (3) Å . In the crystal, molecules are linked by intermolecular N-HÁ Á ÁN hydrogen bonds, generating chains.

Related literature
For general background to the biological activity of 1,4dihydropyridine derivatives, see: Gaudio et al. (1994).

Refinement
All hydrogen atoms bound to aromatic carbon atoms were refined in calculated positions using a riding model with a C-H distance of 0.93 Å and U iso = 1.2U eq (C). For methyl groups C-H distances were 0.96 Å and U iso = 1.5U eq (C) . Two of the methyl groups were found to have two sets of methyl hydrogens and were refined with AFIX 127 and major part occupanices that refined to 0.60 (2) and 0.59 (2) for C17 and C18, respectively. The hydrogen atom attached to the hydropyridine nitrogen was freely refined.

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 > 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. (