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

In the title compound, C18H15FO4S, the fluorobenzene ring makes a dihedral angle of 4.3 (1)° with the mean plane of the benzofuran fragment. In the crystal, molecules are linked by weak intermolecular C—H⋯O hydrogen bonds. The O atom of the sulfinyl group is disordered over two orientations, with site-occupancy factors of 0.940 (3) and 0.060 (3).

In the title compound, C 18 H 15 FO 4 S, the fluorobenzene ring makes a dihedral angle of 4.3 (1) with the mean plane of the benzofuran fragment. In the crystal, molecules are linked by weak intermolecular C-HÁ Á ÁO hydrogen bonds. The O atom of the sulfinyl group is disordered over two orientations, with site-occupancy factors of 0.940 (3) and 0.060 (3).   Table 1 Hydrogen-bond geometry (Å , ).

Comment
Recently, substituted benzofuran derivatives have drawn much attention due to their valuable pharmacological properties such as antibacterial and antifungal, antitumor and antiviral, and antimicrobial activities (Aslam et al., 2009, Galal et al., 2009, Khan et al., 2005. These benzofuran derivatives occur in a wide range of natural products (Akgul & Anil, 2003;Soekamto et al., 2003). As a part of our ongoing study of 5,6-(methylenedioxy)benzofuran derivatives containing either 3-methylsulfinyl (Choi et al., 2010a) or 3-ethylsulfinyl (Choi et al., 2010b substituents, we report herein the crystal structure of the title compound. In the title molecule ( Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.006 (1) Å from the least-squares plane defined by the nine constituent atoms.  Experimental 77% 3-chloroperoxybenzoic acid (224 mg, 1.0 mmol) was added in small portions to a stirred solution of 2-(4-fluorophenyl)-3-isopropylsulfanyl-5,6-methylenedioxy-1-benzofuran (251 mg, 0.8 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 at reduced pressure. The residue was purified by column chromatography (hexane-ethyl acetate, 1:2 v/v) to afford the title compound as a colorless solid [yield 71%, m.p. 437-438 K; R f = 0.55 (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 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 the aryl, 1.00 Å for the methine, 0.99 Å for the methylene, and 0.98 Å for the methyl H atoms. U iso (H) =1.2U eq (C) for the aryl, methine, and methylene H atoms, and 1.

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.