3-(4-Fluorophenylsulfinyl)-2,5,7-trimethyl-1-benzofuran

In the title molecule, C17H15FO2S, the O atom and the 4-fluorophenyl group of the 4-fluorophenylsulfinyl substituent lie on opposite sides of the benzofuran fragment. The mean planes of the benzofuran and 4-fluorophenyl fragments form a dihedral angle of 86.07 (4)°. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers, which are further linked via intermolecular C—H⋯π interactions.

In the title molecule, C 17 H 15 FO 2 S, the O atom and the 4fluorophenyl group of the 4-fluorophenylsulfinyl substituent lie on opposite sides of the benzofuran fragment. The mean planes of the benzofuran and 4-fluorophenyl fragments form a dihedral angle of 86.07 (4) . In the crystal structure, weak intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into centrosymmetric dimers, which are further linked via intermolecular C-HÁ Á Á interactions.

Experimental
Cg is the centroid of the C2-C7 ring.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CV2691).
The benzofuran unit is essentially planar, with a mean deviation of 0.007 (1) Å from the least-squares plane defined by the nine constituent atoms. The 4-fluorophenyl ring is almost perpendicular to the plane of the benzofuran fragment [86.07 (4)°] and is tilted slightly towards it. The crystal packing ( Fig. 2) is stabilized by a weak intermolecular C-H···O hydrogen bond between the 4-fluorophenyl H atom and the oxygen of the S═O unit (Table 1). The molecular packing ( Fig. 2) is further stabilized by an intermolecular C-H···π interaction between the methyl H atom and the benzene ring of an adjacent benzofuran system, with a C11-H11B···Cg ii (Table 1; Cg is the centroid of the C2-C7 benzene ring).

Experimental
77% 3-Chloroperoxybenzoic acid (291 mg, 1.3 mmol) was added in small portions to a stirred solution of 3-(4-fluorophenylsulfanyl)-2,5,7-trimethyl-1-benzofuran (343 mg, 1.2 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 3h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified by column chromatography (hexane-ethyl acetate, 1:1 v/v) to afford the title compound as a colorless solid [yield 82%, m.p. 433-434 K; R f = 0.65 (hexane-ethyl acetate, 1:1 v/v)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in ethyl acetate at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aryl and 0.98 Å for methyl H atoms. U iso (H) = 1.2U eq (C) for aryl and 1.5U eq (C) for methyl H atoms.

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.