1,1′-[4-(2-Methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl]diethanone

In the title compound, C18H21NO3, the 1,4-dihydropyridine ring exhibits a flattened boat conformation. The methoxyphenyl ring is nearly planar [r.m.s. deviation = 0.0723 (1) Å] and is perpendicular to the base of the boat [dihedral angle = 88.98 (4)°]. Intermolecular N—H⋯O and C—H⋯O hydrogen bonds exist in the crystal structure.

Nifedipine, Nitrendipine and Nimodipine etc., have found commercial utility as calcium channel blockers (Böcker & Guengerich, 1986;Gordeev et al., 1996). For the treatment of congestive heart failure a number of DHP calcium antagonists have been introduced (Vo et al., 1995). Some of DHPs have been introduced as a neuroprotectant and cognition enhancer.
In addition, a number of DHPs with platelet antiaggregatory activity have also been discovered (Cooper et al., 1992).
The configuration and conformation of the title compound, (I) and the atom numbering scheme are shown in the ORTEP drawing ( Fig. 1). The 1,4-DHP ring exhibits a flattened boat conformation, with atoms N1 and C4 displaced by -0.165 (2) and -0.420 (2) Å, respectively, from the least-squares plane defined by the remaining four atoms of the DHP ring. The maximum deviation of these latter four atoms (C2/C3/C5/C6) from their mean plane is 0.015 (1)  In the crystal structure, intermolecular N-H···O, C-H···O hydrogen bonds (Table 1; Fig. 2) are observed, where the N-H···O bond generates a graph set motif of C(6) (Bernstein et al., 1995), forming an infinite chain along the b axis.
Experimental 3,5-diacetyl-2,6-dimethyl-1,4-dihydro-4-(2-methoxyphenyl)-pyridine was prepared according to the Hantzsch pyridine synthesis. 2-methoxybenzaldehyde (10 mmol), acetylacetone (20 mmol) and ammonium acetate (10 mmol) are taken in 1: 2: 1 mole ratio along with ethanol (25 ml) as a solvent in a RB-flask and refluxed in steam-bath until the color of the solution changes to reddish-orange (approximately 2 h). This mixture is kept under ice cold conditions to obtain the solid product, which is extracted using diethyl ether and acetone, then excess solvent was distilled off. The purity of the crude product was checked through TLC and recrystallized using an acetone and diethyl ether (1:1) solvent mixture. Yield 89.7%, M.P.

Refinement
The N-bound H atom was located in a difference Fourier map and its positional parameters were refined. The H atoms were placed in calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.98 Å.U iso = 1.2U eq (C) for CH and U iso = 1.5U eq (C) for CH 3 groups.  Fig. 1. The molecular structure of title compound with atom numbering scheme and 30% probability displacement ellipsoids.