2-Amino-7,7-dimethyl-5-oxo-4-[3-(trifluoromethyl)phenyl]-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile

In the title molecule, C19H17F3N2O2, the fused cyclohexene and pyran rings adopt sofa and flattened boat conformations, respectively. The four essentially planar atoms of the pyran ring [maximum deviation = 0.008 (2) Å] form a dihedral angle of 88.13 (9)° with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over three sets of sites in a 0.507 (7):0.330 (7):0.163 (3) ratio. In the crystal, molecules are connected into inversion dimers via pairs of N—H⋯N hydrogen bonds and these dimers are further linked by N—H⋯O hydrogen bonds into a two-dimensional network parallel to (100).

In the title molecule, C 19 H 17 F 3 N 2 O 2 , the fused cyclohexene and pyran rings adopt sofa and flattened boat conformations, respectively. The four essentially planar atoms of the pyran ring [maximum deviation = 0.008 (2) Å ] form a dihedral angle of 88.13 (9) with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over three sets of sites in a 0.507 (7):0.330 (7):0.163 (3) ratio. In the crystal, molecules are connected into inversion dimers via pairs of N-HÁ Á ÁN hydrogen bonds and these dimers are further linked by N-HÁ Á ÁO hydrogen bonds into a twodimensional network parallel to (100).   Table 1 Hydrogen-bond geometry (Å , ).

Experimental
In a 50 ml round bottom flask charged with 1mmole of dimedone, 1 mmole of 3-(trifluoromethyl)benzaldehyde and 1 mmole of malononitrile were added. Then 5 ml of aqueous ethanol (1:1) and 20 mol% of NH 4 Cl was added and the reaction mixture stirred for 30-45 min. at 323-328 K. The reaction was monitored by TLC. After completion of the reaction, the mixture was poured onto crushed ice and stirred. The solid precipitated was filtered and recrystallized from ethanol to afford pure product as crystal suitable for X-ray diffraction. m.p.: 503-504 K, Yield: 82%.

Refinement
All H atoms were positioned geometrically and were treated as riding on their parent C/N atoms, with C-H distances of 0.93-0.98 Å, N-H distances of 0.86 Å and with U iso (H) = 1.2U eq (C/N) or 1.5U eq (methyl C).

Figure 1
The molecular structure of the title compound with ellipsoids drawn at the 40% probability level. H atoms are shown as small spheres of arbitrary radii. The F atoms are disorded over three sets of sites.  The packing arrangement of molecules viewed along the a axis. The dashed lines show intermolecular N-H···O and N-H···N hydrogen bonds. The disorder is not shown. 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 > 2sigma(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. (