Ethyl 2-(5-fluoro-3-methylsulfinyl-1-benzofuran-2-yl)acetate

In the title compound, C13H13FO4S, the O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment. The crystal structure exhibits four intermolecular non-classical C—H⋯O hydrogen bonds. In addition, the crystal structure contains aromatic π–π interactions between the furan and benzene rings of adjacent molecules [centroid–centroid distance = 3.743 (2) Å], and two intermolecular C—H⋯π interactions.

In the title compound, C 13 H 13 FO 4 S, the O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment. The crystal structure exhibits four intermolecular non-classical C-HÁ Á ÁO hydrogen bonds. In addition, the crystal structure contains aromaticinteractions between the furan and benzene rings of adjacent molecules [centroid-centroid distance = 3.743 (2) Å ], and two intermolecular C-HÁ Á Á interactions.
The benzofuran unit is essentially planar, with a mean deviation of 0.010 (1) Å from the least-squares plane defined by the nine constituent atoms. The crystal packing ( Fig. 2) exhibits weak intermolecular C-H···O non-classical hydrogen bonds; the first between an H atom of the benzofuran ring and the S═O unit, with a C3-H3···O4 i , the second between an H atom of benzofuran ring and the C═O unit, with a C5-H5···O3 ii , the third between an H atom of the methylene group bonded to carboxylate C atom and the S═O unit, with a C9-H9A···O4 iii , the fourth between an H atom of the methylene group bonded to carboxylate C atom and the furan O atom, with a C9-H9B···O1 iv , respectively (Table 1 and Fig. 2). Additionally, the crystal packing ( Fig. 3) contains aromatic π-π interactions between the furan and the benzene rings of the neighbouring molecules, with a Cg1···Cg2 vi distance of 3.743 (2) Å (Cg1 and Cg2 are the centroids of the C1/C2/C7/O1/C8 furan ring and the C2-C7 benzene ring, respectively). The molecular packing is further stabilized by two intermolecular C-H···π interactions; the first between the methylene H atom of ethoxy group and the benzene ring of a neighbouring molecule (C11-H11A···Cg2 v ), the second between the methyl H atom of ethoxy group and the furan ring of a neighbouring molecule (C12-H12C···Cg1 v ), respectively (Table 1 and Fig. 3).
Experimental 77% 3-chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of ethyl 2-(5-fluoro-3-methylsulfanyl-1-benzofuran-2-yl)acetate (268 mg, 1.0 mmol) in dichloromethane (30 ml) at 273 K. After being stirred for 4 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 79%, m.p. 401-402 K; R f = 0.43 (hexane-ethyl acetate, 1;2 v/v )]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in acetone at room temperature.
supplementary materials sup-2 Refinement All H atoms were geometrically positioned and refined using a riding model, with C-H = 0.93 Å for the aryl, 0.97 Å for the methylene, and 0.96 Å for the methyl H atoms. U iso (H) = 1.2U eq (C) for the aryl and methylene H atoms, and 1.5U eq (C) for methyl H atoms. 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.