3-Amino-1-(4-fluorophenyl)-8-methoxy-1H-benzo[f]chromene-2-carbonitrile

The title compound, C21H15FN2O2, features an approximately planar 1H-benzo[f]chromene fused-ring system (r.m.s. deviation for the 14 non-H atoms = 0.052 Å), with the fluorobenzene ring being almost perpendicular to this [dihedral angle = 85.30 (7) °]. The furan ring has a flattened half-chair conformation, with the methine C atom deviating by 0.132 (2) Å from the plane of the remaining atoms (r.m.s. deviation = 0.0107 Å). In the crystal, inversion dimers are formed via pairs of amine–cyano N—H⋯N hydrogen bonds. The dimers are connected into a three-dimensional architecture by C—H⋯N(cyano), C—H⋯π and π–π [intercentroid distance = 3.6671 (10) Å] interactions.


T. Tiekink Comment
Benzo-and naphthopyran-derivatives can possess biological and pharmacological activities, such as anti-coagulant, spasmolytic, diuretic, anti-cancer and anti-anaphylactin activities (Bonsignore et al., 1993). Some of these compounds can also be employed as cosmetics, pigments and as potential biodegradable agrochemicals (Hafez, et al., 1987).
Derivatives of 4H-pyran are also known to exhibit biological activities Sabry et al., 2011), and form the focus of on-going studies of their chemistry. In this connection, herein, the crystal and molecular structure of the title compound, (I), is described.

Experimental
A solution of 6-bromo-2-naphthol (0.01 mol) in EtOH (30 ml) was treated with α-cyano-p-fluorocinnamonitrile (0.01 mol) and piperidine (0.5 ml). The reaction mixture was heated until complete precipitation occurred corresponding to a reaction time of 60 min. The solid product which formed was collected by filtration and recrystallized from ethanol to give the title compound, (I), in the form of light brown prisms; M.pt: 529-530 K.

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.93-0.98 Å) and refined as riding with U iso (H) = 1.2U eq (C).

Figure 1
The molecular structure of (I) showing displacement ellipsoids at the 35% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.