3-Amino-1-(4-fluorophenyl)-7-methoxy-1H-benzo[f]chromene-2-carbonitrile

In the title compound, C21H15FN2O2, the furan ring has a flattened half-chair conformation [the methine C atom lies 0.136 (2) Å above the C5 plane which has an r.m.s. deviation of 0.0229 Å]. Overall, the 1H-benzo[f]chromene fused-ring system approximates a plane (r.m.s. deviation of the 14 non-H atoms = 0.049 Å). The fluorobenzene ring is almost perpendicular to this plane [dihedral angle = 89.58 (8)°]. Zigzag supramolecular tapes along the b axis are the most notable feature of the crystal packing. This arises through an alternating sequence of 12-membered {⋯HNC3N}2 and eight-membered {⋯HNCO}2 synthons. These are connected into a three-dimensional architecture by π–π [intercentroid distance for centrosymmetrically related fluorobenzene rings = 3.5181 (10) Å] and C—H⋯π interactions.

Cg1 is the centroid of the C15-CC20 ring.

Experimental
A solution of 7-methoxy-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 (reaction time: 60 min). The solid product which formed was collected by filtration and recrystallized from ethanol to give the title compound, (I), as light-brown prisms; M.pt: 533-534 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).
The N-bound-H atoms were refined freely.

Figure 1
The molecular structure of (I) showing displacement ellipsoids at the 35% probability level.   interactions are shown as blue, orange, brown and purple dashed lines, respectively.

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.