Crystal structure of 2-amino-4-(4-chlorophenyl)-1-(4-methylphenyl)-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carbonitrile

In the title compound, C23H20ClN3O, each of the cyclohexene and 1,4-dihydropyridine rings of the 1,4,5,6,7,8-hexahydroquinoline ring system adopts a twisted-boat conformation. The dihedral angle between the two benzene rings is 11.52 (7)°. In the crystal, molecules are linked through a pair of amino–nitrile N—H⋯N hydrogen bonds, forming inversion dimers. These assemble into a three-dimensional network via C—H⋯O and C—H⋯π interactions.

In the crystal, a pair of N-H···N intermolecular hydrogen bonds connects two molecules by an R 2 2 (12) ring motif (Table 1), forming a centrosymmetric dimer (Fig. 2). Weak C-H···O and C-H···π interactions connect the dimers to each other, forming a three-dimensional network.

S2. Experimental
To a solution of 1.3-cyclohexanedione (3.36 g, 0.03 mol) in 40 ml ethanol, p-toluidine (3.21 g, 0.03 mol) and catalytic a amount of triethylamine were added. The mixture was heated under reflux for 3 h. (4-Chlorobenzylidene)malononitrile (5.68 g, 0.03 mol) was added to the reaction mixture and refluxed for another 3 h.

Figure 1
Molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.

Figure 2
View of the dimers formed by N-H···N hydrogen bonds down the b axis.

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 e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.