3-(4-Bromophenylsulfonyl)-5-ethyl-2-methyl-1-benzofuran

In the title compound, C17H15BrO3S, the 4-bromophenyl ring makes a dihedral angle of 76.58 (9)° with the mean plane [r.m.s. deviation = 0.006 (2) Å] of the benzofuran fragment. In the crystal, molecules are linked by weak C—H⋯O and C—H⋯π interactions.

The title compound crystallizes as the non-centrosymmetric space group P4 3 in spite of having no asymmetric C atoms.
In the title molecule ( Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.006 (2) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle between the 4-bromophenyl ring and the mean plane of the benzofuran ring is 76.58 (9)°. In the crystal structure ( Fig. 2), molecules are connected by weak C-H···O and C-H···π interactions (Table 1, Cg is the centroid of the C2-C7 benzene ring).

Experimental
3-Chloroperoxybenzoic acid (77%, 448 mg, 2.0 mmol) was added in small portions to a stirred solution of 3-(4-bromophenylsulfanyl)-5-ethyl-2-methyl-1-benzofuran (312 mg, 0.9 mmol) in dichloromethane (50 mL) at 273 K. After being stirred at room temperature for 10h, 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 68%, m.p. 404-405 K; R f = 0.61 (benzene)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in diisopropyl ether at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aryl, 0.99 Å for methylene and 0.98 Å for methyl H atoms, respectively. U iso (H) = 1.2U eq (C) for aryl, methylene, and 1.5U eq (C) for methyl H atoms. The positions of methyl hydrogens were optimized rotationally.    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.35 e Å −3 Δρ min = −0.29 e Å −3 Absolute structure: Flack (1983), 1000 Friedel pairs Flack parameter: 0.001 (7) 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