1-(2-Fluorophenyl)-6,7-dimethoxyisochroman

In the title compound, C17H17FO3, the benzene ring of the isochroman unit is inclined at 84.96 (7)° to the fluorobenzene ring plane, and the pyran ring adopts a half-boat conformation. In the crystal structure, C—H⋯O hydrogen bonds link molecules into rows along the c axis, while C—H⋯O interactions and C—H⋯F hydrogen bonds to the fluorine acceptor stack the molecules down the b axis. In addition, the crystal structure exhibits a weak C—H⋯π interaction between a methyl H atom of the methoxy group and the dimethoxybenzene ring of an adjacent molecule.

In the title compound, C 17 H 17 FO 3 , the benzene ring of the isochroman unit is inclined at 84.96 (7) to the fluorobenzene ring plane, and the pyran ring adopts a half-boat conformation. In the crystal structure, C-HÁ Á ÁO hydrogen bonds link molecules into rows along the c axis, while C-HÁ Á ÁO interactions and C-HÁ Á ÁF hydrogen bonds to the fluorine acceptor stack the molecules down the b axis. In addition, the crystal structure exhibits a weak C-HÁ Á Á interaction between a methyl H atom of the methoxy group and the dimethoxybenzene ring of an adjacent molecule.
The pyran ring of (I) adopts a half-boat conformation (Cremer & Pople, 1975) with the O1 atom 0.639 (3) Å from the least-squares plane through atoms C1-C3, C8, C9. The r.m.s. deviation from this plane was 0.083 Å. The benzene ring of the isochroman unit is inclined at 84.96 (7) ° to the fluorobenzene ring plane. Both the C and O atoms of the two methoxy substituents lie close to the aromatic ring plane (maximum deviation 0.310 (5) Å for C16).
In the molecular packing (Fig. 2), C17-H17B···O1 hydrogen bonds link the molecules into rows along the c axis ( Fig.   2 and Table 1; symmetry codes as in Fig. 2). The F1 atom acts as an acceptor in a C7-H7···F1 hydrogen bond that, together with C1-H1B···O2 interactions, stacks molecules from individual rows down the the b axis (Fig. 2, Fig 3 and Table 1; symmetry codes as in Fig. 2). Additionally, a weak C-H···π interaction in the structure was observed between a methyl H atom of the methoxy group and the dimethoxybenzene ring of an adjacent molecule, with a C17-H17A···Cg i separation of 2.70 Å (Table 1 and Fig. 2; Cg is the centroid of the C3-C8 benzene ring, symmetry codes as in Fig. 2).)

Experimental
A homogenized mixture of 2-(3,4-dimethoxyphenyl)ethanol (0.18g, 1 mmol) and 4-fluorobenzaldehyde (0.12g 1 mmol) and a catalytic amount of p-toluenesulfonic acid monohydrate was irradiated for 1.3 min. The product was purified by thin layer chromatography using petroleum ether and ethyl acetate (7:2 v:v) to afford the title compound ( All H-atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.95 Å, U iso =1.2U eq (C) for aromatic 1.00 Å, U iso = 1.2U eq (C) for CH, 0.99 Å, U iso = 1.2U eq (C) for CH 2 and 0.98 Å, U iso = 1.5U eq (C) for CH 3 hydrogen atoms. Fig. 1. The molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.

Special details
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