Crystal structure of 2-amino-7-hydroxy-4-(4-hydroxyphenyl)-4H-chromene-3-carbonitrile

In the title compound, C16H12N2O3, the chromene ring system is nearly planar [maximum deviation from the mean plane = 0.057 (1) Å], and is almost perpendicular to the benzene ring, with a dihedral angle of 85.29 (5)°. In the crystal, molecules are linked by classical N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds, and weak C—H⋯O hydrogen bonds, forming a three-dimensional supramolecular network. Furthermore, a weak π–π stacking interaction is observed; the centroid-to-centroid distance is 3.7260 (7) Å.

Interestingly, 2-amino-4H-chromene derivatives arises from their potential application in the treatment of human inflammatory TNFa-mediated diseases, such as psoriatic arthritis and rheumatoid and in cancer therapy (Skommer et al., 2006;Gourdeau et al., 2004;Anderson et al., 2005;Wang et al., 2000). Such facts inspired us to synthesize and determine the crystal structure of the title compound in this study.

S2. Experimental
A mixture of 1 mmol (180 mg) of 4-hydroxybenzylidene-malononitrile and 1 mmol (110 mg) of resorcinol was refluxed in 10 ml e thanol for 3 h in the presence of few catalytic drops of pipredine. The mixture was cooled at ambient temperature and the resulting solid was filtered off, dried under vacuum and recrytallized from ethanol to furnish white crystals in a good quality suitable for X-ray diffraction. Mp 523 K.

S3. Refinement
The H atoms of the OH and NH 2 groups were located in a difference Fourier map and were refined freely [O2-H2O = 0.893 (17)  View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.

Figure 2
The packing diagram of the title compound viewed 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.