2-Amino-4-(4-methylphenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile

The 4H-pyran ring of the title compound, C17H16N2O2, is nearly planar [maximum deviation = 0.077 (2) Å] and the cyclohexene ring adopts a flattened chair conformation [puckering parameters: Q T = 0.435 (2) Å, θ = 122.0 (3)° and ϕ = 53.5 (3)°]. The 4H-pyran ring is almost perpendicular to the benzene ring [dihedral angle = 87.23 (8)°] and is almost coplanar with the mean plane of the cyclohexene ring [dihedral angle = 8.01 (8)°]. In the crystal, inversion-related molecules are linked by pairs of intermolecular N—H⋯N hydrogen bonds, forming inversion dimers with R 2 2(12) ring motifs. These dimers are further connected by N—H⋯O and C—H⋯N hydrogen bonds, forming a layer structure extending parallel to (0-12). Molecules within the layers interact with each other via C—H⋯π interactions.

This project was supported financially by the Higher Education Ministry of Egypt in collaboration with Manchester Metropolitan University. We thank Sargodha and Erciyes Universities for providing X-ray analysis and data refinement facilities. properties (Symeonidis et al., 2009;Narender & Gupta, 2009;Alvey, et al., 2009). In a continuation to our on-going study of the synthesis and biological characterization of a new series of tetrahydro-4-chromenes (Mohamed et al., 2012a,b,c), we report here the synthesis and crystal structure of the title compound (I).
As seen in Fig. 1, the C12-C17 cyclohexene ring of (I) is in a flattened chair conformation [puckering parameters (Cremer & Pople, 1975) ring is nearly planar with a maximum deviation of 0.077 (2) Å for C8 and is almost perpendicular to the C1-C6 benzene ring [dihedral angle = 87.23 (8)°] and is almost co-planar with the mean plane of the cyclohexene ring [dihedral angle = 8.01 (8) °]. All bond lengths (Allen et al., 1987) and angles of (I) are within normal ranges and are comparable to similar structures (Yadav et al., 2009;Mohamed et al., 2012a,b,c).
In the crystal, a pair of intermolecular N-H···N hydrogen bonds link the main molecules into an inversion dimer, generating an R 2 2 (12) graph-set motif (Bernstein et al., 1995; Table 1, Fig. 2). The dimers are further connected by N-H···O and C-H···N hydrogen bonds, forming a layer of molecules parallel to (0 -1 2) ( Table 1, Fig. 2). In addition, the layers are interconnected by weak C-H···π interactions.

Experimental
A mixture of 168 mg (1 mmol) (4-methybenzylidene)propanedinitrile, 112 mg (1 mmol) cyclohexane-1,3-dione in presence of 61 mg ethanolamine as catalyst was refluxed in 40 ml ethanol. The reaction mixture was monitored by TLC till completion after 6 h. A solid product was deposited on cooling at room temperature and collected by filtration. The crude product was recrystallized from ethanol in excellent yield (89%). Single crystals suitable for X-ray analysis were grown upon slow evaporation of the solution of (I) in ethanol over two days [M.p.: 477 K].

Figure 1
The molecular structure of the title compound showing the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.20 e Å −3 Δρ min = −0.17 e Å −3 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.