5-Chloro-2-(4-chlorophenyl)-7-methyl-3-methylsulfinyl-1-benzofuran

In the title compound, C16H12Cl2O2S, the O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment. The 4-chlorophenyl ring is rotated out of the benzofuran plane, as indicated by the dihedral angle of 15.91 (4)°. In the crystal, molecules are linked into chains along the b axis by weak intermolecular C—H⋯O hydrogen bonds.

In the title compound, C 16 H 12 Cl 2 O 2 S, the O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment. The 4chlorophenyl ring is rotated out of the benzofuran plane, as indicated by the dihedral angle of 15.91 (4) . In the crystal, molecules are linked into chains along the b axis by weak intermolecular C-HÁ Á ÁO hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2648).
The benzofuran unit is essentially planar, with a mean deviation of 0.013 (1) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle formed by the plane of the benzofuran and the 4-chlorophenyl ring is 15.91 (4)°. The crystal packing ( Fig. 2) is stabilized by a weak intermolecular C-H···O hydrogen bond between the methyl H atom and the oxygen of the S═O unit, with a C15-H15A···O2 i (Table 1).
Experimental 77% 3-Chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of 5-chloro-2-(4chlorophenyl)-7-methyl-3-methylsulfanyl-1-benzofuran (323 mg, 1.0 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 (hexane-ethyl acetate, 1:1 v/v) to afford the title compound as a colorless solid [yield 79%, m.p. 456-457 K; R f = 0.62 (hexane-ethyl acetate, 1:1 v/v)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in tetrahydrofuran at room temperature.

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