3-Ethylsulfinyl-2-(4-fluorophenyl)-5,6-methylenedioxy-1-benzofuran

In the title compound, C17H13FO4S, the 4-fluorophenyl ring makes a dihedral angle of 4.92 (4)° with the plane of the 5,6-methylenedioxy-1-benzofuran fragment. In the crystal, molecules are linked by weak intermolecular C—H⋯O and C—H⋯F hydrogen bonds.

In the title compound, C 17 H 13 FO 4 S, the 4-fluorophenyl ring makes a dihedral angle of 4.92 (4) with the plane of the 5,6methylenedioxy-1-benzofuran fragment. In the crystal, molecules are linked by weak intermolecular C-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FL2302).
The 5,6-(methylenedioxy)benzofuran unit is essentially planar, with a mean deviation of 0.013 (1) Å from the leastsquares plane defined by the twelve constituent atoms. The dihedral angle formed by this plane and the 4-fluorophenyl ring is 4.92 (4)°. The molecular packing (Fig. 2) is stabilized by intermolecular C-H···O hydrogen bonds; the first one between the 4-fluorophenyl H atom and the oxygen of the S═O unit, with a C12-H12···O4 i , the second one between the methyl H atom of ethyl group and the oxygen of the S═O unit, with a C17-H17B···O4 iii , respectively (Table 1). The crystal packing ( Fig. 2) is further stabilized by intermolecular C-H···F hydrogen bonds between the methylene H atom of ethyl group and the fluorine, with a C16-H16A···F ii (Table 1).

Experimental
77% 3-Chloroperoxybenzoic acid (202 mg, 0.9 mmol) was added in small portions to a stirred solution of 3-ethylsulfanyl-2-(4-fluorophenyl)-5,6-methylenedioxy-1-benzofuran (253 mg, 0.8 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 4h, 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 (silica gel, ethyl acetate) to afford the title compound as a colorless solid [yield 79%, m.p. 449-450 K; Rf = 0.61 (ethyl acetate)]. 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 positioned geometrically 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.
supplementary materials sup-2 Figures Fig. 1. 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 a 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S 0.03741 (5)