3-(4-Chlorophenylsulfonyl)-5-isopropyl-2-methyl-1-benzofuran

In the title molecule, C18H17ClO3S, the 4-chlorophenyl ring makes a dihedral angle of 77.03 (5)° with the mean plane of the benzofuran fragment. In the crystal structure, the molecules are linked by weak intermolecular C—H⋯O hydrogen bonds and C—H⋯π interactions

In the title molecule, C 18 H 17 ClO 3 S, the 4-chlorophenyl ring makes a dihedral angle of 77.03 (5) with the mean plane of the benzofuran fragment. In the crystal structure, the molecules are linked by weak intermolecular C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions

Comment
Many compounds containing a benzofuran ring have recently drawn considerable attention due to their interesting 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 compounds occur in a wide range of natural products (Akgul & Anil, 2003;Soekamto et al., 2003). As a part of our ongoing program of the substituent effect on the solid state structures of 3-arylsulfonyl-5-isopropyl-2-methyl-1-benzofuran analogues (Choi et al., 2008(Choi et al., , 2010, 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 0.007 (1) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle formed by the 4-chlorophenyl ring and the mean plane of the benzofuran fragment is 77.03 (5)°. The crystal packing ( Fig. 2) is stabilized by weak intermolecular C-H···O hydrogen bonds between a methyl H atom and the O atom of the sulfonyl group (Table 1; C12-H12C···O3 i ).
The crystal packing (Fig. 3) is further stabilized by intermolecular C-H···π interactions between a methyl H atom of the isopropyl group and the benzene ring of an adjacent molecule (Table 1; C10-H11B···Cg ii , Cg is the centroid of the C2-C7 benzene ring).

Experimental
77% 3-chloroperoxybenzoic acid (560 mg, 2.5 mmol) was added in small portions to a stirred solution of 3-(4-chlorophenylsulfanyl)-5-isopropyl-2-methyl-1-benzofuran (380 mg, 1.2 mmol) in dichloromethane (40 ml) at 273 K. After being stirred at room temperature for 6 h, 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 colourless solid [yield 71%, m.p. 409-410 K; R f = 0.65 (benzene)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in acetone at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model: C-H = 0.93 Å for aryl, 0.98 Å for methine, and 0.96 Å for methyl H atoms, with U iso (H) = 1.2U eq (C) for aryl and methine, 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.