2-(4-Fluorophenyl)-5,6-methylenedioxy-3-methylsulfinyl-1-benzofuran

In the title compound, C16H11FO4S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the mean plane through the 5,6-(methylenedioxy)benzofuran fragment. The 4-fluorophenyl ring is rotated out of the 5,6-(methylenedioxy)benzofuran plane, making a dihedral angle of 29.90 (6)°. In the crystal structure, both intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers. The combination of C—H⋯O hydrogen bonds result in chains running along [1 ].

In the title compound, C 16 H 11 FO 4 S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the mean plane through the 5,6-(methylenedioxy)benzofuran fragment. The 4-fluorophenyl ring is rotated out of the 5,6-(methylenedioxy)benzofuran plane, making a dihedral angle of 29.90 (6) . In the crystal structure, both intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into centrosymmetric dimers. The combination of C-HÁ Á ÁO hydrogen bonds result in chains running along [111].
As a part of our ongoing studies of the effect of side chain substituents on the solid state structures of 5,6-methylenedioxy-1-benzofuran analogues (Choi et al., 2007(Choi et al., ,2009), we report the crystal structure of the title compound (Fig.1).
The 5,6-(methylenedioxy)benzofuran unit is essentially planar, with a mean deviation of 0.060 (2) Å from the least-squares plane defined by the twelve constituent atoms. The dihedral angle formed by the plane of the 5,6-(methylenedioxy)benzofuran ring and the plane of 4-fluorophenyl ring is 29.90 (6).

Experimental
77% 3-chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of 2-(4-fluorophenyl)-5,6-methylenedioxy-3-methylsulfanyl-1-benzofuran (302 mg, 1.0 mmol) in dichloromethane (30 ml) at 273 K. After being stirred at room temperature for 2h, 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 71%, m.p. 488-489 K; R f = 0.51 (hexane-ethyl acetate, 1:2 v/v)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in chloroform at room temperature.

Refinement
All H atoms were geometrically positioned and refined using a riding model, with C-H = 0.93 Å for aryl, 0.97 Å for methylene, and 0.96 Å for methyl H atoms. U iso (H) = 1.2U eq (C) for aryl and methylene H atoms, 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.