5-Bromo-2,7-dimethyl-3-methylsulfinyl-1-benzofuran

In the title compound, C11H11BrO2S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the plane of the benzofuran fragment. The crystal structure is stabilized by non-classical intermolecular C—H⋯O hydrogen bonding, and by intermolecular C—Br⋯π interactions, with C—Br⋯Cg = 3.629 Å (Cg is the centroid of the benzene ring). In addition, the crystal structure exhibits aromatic π–π interactions between the furan rings of neighbouring molecules [centroid–centroid distance = 4.206 (6) Å].

In the title compound, C 11 H 11 BrO 2 S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the plane of the benzofuran fragment. The crystal structure is stabilized by non-classical intermolecular C-HÁ Á ÁO hydrogen bonding, and by intermolecular C-BrÁ Á Á interactions, with C-BrÁ Á ÁCg = 3.629 Å (Cg is the centroid of the benzene ring). In addition, the crystal structure exhibits aromaticinteractions between the furan rings of neighbouring molecules [centroid-centroid distance = 4.206 (6) Å ].

Comment
Benzofuran ring systems are widely occurring in natural products (Akgul & Anil, 2003;von Reuss & König, 2004) and in synthetic substances which exhibit a variety of pharmacological properties (Howlett et al., 1999). As a part of our continuing studies of the effect of side chain substituents on the solid state structures of 5-halo-2-methyl-3-methylsulfinyl-1-benzofuran analogues (Choi et al., 2007a,b), the crystal structure of the title compound has been determined ( Fig. 1).
The benzofuran unit is essentially planar, with a mean deviation of 0.009 (4) Å from the least-squares plane defined by the nine constituent atoms. The molecular packing ( Fig. 2) is stabilized by non-classical intermolecular C-H···O hydrogen bond between the methyl H atom of the methylsulfinyl substituent and the oxygen of the S═O unit, with a C11-H11B···O2 i ( Table 1). The crystal packing ( Fig. 2) is further stabilized by intermolecular C-Br···π interaction between the Br atom and the benzene ring of an adjacent molecule, with a C4-Br···Cg2 ii distance of 3.629Å (Cg2 is the centroid of the C2-C7 benzene ring). Additionally, the molecular packing ( Fig. 2) exhibits aromatic π-π interaction between the furan rings of neighbouring molecules, with a Cg1···Cg1 i distance of 4.206 Å (Cg1 is the centroid of the C1/C2/C7/O1/C8 furan ring).
Experimental 77% 3-chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of 5-bromo-2,7-dimethyl-3-methylsulfanyl-1-benzofuran (287 mg, 1.0 mmol) in dichloromethane (30 ml) at 273 K. After being stirred for 3 h at room temperature, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified by column chromatography (ethyl acetate) to afford the title compound as a colorless solid [yield 83%, m.p. 411-412 K; R f = 0.33 (ethyl acetate)]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in chloroform at room temperature.

Refinement
All H atoms were geometrically positioned and refined using a riding model, with C-H = 0.93 Å for the aryl and 0.96 Å for the methyl H atoms. U iso (H) = 1.2Ueq(C) for the aryl and 1.5U eq (C) for the 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 cycles 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.