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

In the title compound, C17H15FO2S, the benzofuran ring system, being essentially planar, with an r.m.s. deviation from the least-squares plane of 0.009 (2) Å, makes a dihedral angle of 79.02 (5)° with the plane of the 2-fluorophenyl group. In the crystal, molecules are linked by pairs of weak C—H⋯O hydrogen bonds into centrosymmetric dimers.

In the title compound, C 17 H 15 FO 2 S, the benzofuran ring system, being essentially planar, with an r.m.s. deviation from the least-squares plane of 0.009 (2) Å , makes a dihedral angle of 79.02 (5) with the plane of the 2-fluorophenyl group. In the crystal, molecules are linked by pairs of weak C-HÁ Á ÁO hydrogen bonds into centrosymmetric dimers.

Related literature
For background information and the crystal structures of related compounds, see: Choi et al. (2010Choi et al. ( , 2011 Table 1 Hydrogen-bond geometry (Å , ).
In the title molecule ( Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.009 (2) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle between the 2-fluorophenyl ring and the mean plane of the benzofuran ring is 79.02 (5)°. In the crystal structure, molecules are connected by pairs of weak C-H..O hydrogen bonds into centrosymmetric dimers (Table 1).

Experimental
3-Chloroperoxybenzoic acid (77%, 269 mg, 1.2 mmol) was added in small portions to a stirred solution of 3-(2-fluorophenylsulfanyl)-2,5,7-trimethyl-1-benzofuran (315 mg, 1.1 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 5h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated at reduced pressure. The residue was purified by column chromatography (benzene) to afford the title compound as a colorless solid [yield 76%, m.p. 394-395 K; R f = 0.46 (benzene)]. 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. The positions of methyl hydrogens were optimized rotationally.  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.  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.