Propyl 2-(5-bromo-3-methylsulfinyl-1-benzofuran-2-yl)acetate

In the title compound, C14H15BrO4S, the S atom has a distorted trigonal–pyramidal coordination. The O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment. The molecules form slightly slipped π-stacked inversion-symmetric dimers by intermolecular aromatic π–π interactions, with a centroid-to-centroid distance of 3.695 (4) Å between the benzene rings of neighbouring molecules. The crystal packing is further stabilized by intermolecular C—H⋯π interactions between the methylene H atoms of the propyl group towards the benzene and furan rings of neighbouring molecules, respectively. Additionally, the crystal structure exhibits weak intermolecular C—H⋯O hydrogen bonds.

In the title compound, C 14 H 15 BrO 4 S, the S atom has a distorted trigonal-pyramidal coordination. The O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment. The molecules form slightly slipped -stacked inversion-symmetric dimers by intermolecular aromaticinteractions, with a centroid-to-centroid distance of 3.695 (4) Å between the benzene rings of neighbouring molecules. The crystal packing is further stabilized by intermolecular C-HÁ Á Á interactions between the methylene H atoms of the propyl group towards the benzene and furan rings of neighbouring molecules, respectively. Additionally, the crystal structure exhibits weak intermolecular C-HÁ Á ÁO hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZL2167).
The benzofuran unit is essentially planar, with a mean deviation of 0.013 (2) Å from the least-squares plane defined by the nine constituent atoms. The molecular packing ( Fig. 2) is stabilized by intermolecular π-π stacking interactions between the benzene rings of neighbouring molecules. Via this interaction the molecules form slightly slipped π-stacked inversion symmetric dimers, with a centroid-centroid distance Cg1···Cg1 iii of 3.695 (4) Å between the benzene rings of neighbouring molecules. (Cg is the centroid of the C2-C7 benzene ring, symmetry code as in Fig. 2). The molecular packing is further stabilized by C-H···π interactions; one between the hydrogen of the C11-methylene group and the benzene ring of the benzofuran unit, with a C11-H11B···Cg1 i separation of 3.02 Å, and a second between the hydrogen of the C12-methylene group and the furan ring of the benzofuran unit, with a C12-H12B···Cg2 i separation of 2.90 Å (Table 1 and  and Cg2 are the centroids of the C2-C7 benzene ring and the C1/C2/C7/O1/C8 furan ring, respectively, symmetry code as in Fig. 2). In addition, three weak intermolecular C-H···O hydrogen bonds in the structure were observed (Table 1 and Fig. 3); one between the hydrogen on benzene ring and the oxygen of the S═O unit (C3-H3···O4 ii ), a second between the hydrogen on benzene ring and the oxygen of the C═O unit (C5-H5···O3 iii ), and a third between the hydrogen of the C9-methylene group and the S═O unit (C9-H9B···O4 iv ), respectively.
Experimental 77% 3-chloroperoxybenzoic acid (179 mg, 0.8 mmol) was added in small portions to a stirred solution of propyl 2-(5-bromo-3-methylsulfanyl-1-benzofuran-2-yl)acetate (629 mg, 0.75 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 (hexane-ethyl acetate, 1:2 v/v) to afford the title compound as a colorless solid [yield 81%, m.p. 413-413.5 K; for methyl H atoms. Fig. 1. The molecular structure of the title compound, showing displacement ellipsoids drawn at the 30% probability level.

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.