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

In the title compound, C14H15FO4S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the plane of the benzofuran fragment which is essentially planar with a mean deviation of 0.008 (1) Å from its least-squares plane. The crystal structure stabilized by three different intermolecular non-classical C—H⋯O hydrogen bonds. The crystal structure also exhibits aromatic π–π interactions between the benzene rings of adjacent benzofuran ring systems [centroid–centroid distance = 3.688 (2) Å]

In the title compound, C 14 H 15 FO 4 S, the O atom and the methyl group of the methylsulfinyl substituent are located on opposite sides of the plane of the benzofuran fragment which is essentially planar with a mean deviation of 0.008 (1) Å from its least-squares plane. The crystal structure stabilized by three different intermolecular non-classical C-HÁ Á ÁO hydrogen bonds. The crystal structure also exhibits aromaticinteractions between the benzene rings of adjacent benzofuran ring systems [centroid-centroid distance = 3.688 (2) Å ]
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BQ2158). properties (Howlett et al., 1999;Twyman & Allsop, 1999). As a part of our ongoing studies of the effect of side chain substituents on the solid state structures of alkyl 2-(5-fluoro-3-methylsulfinyl-1-benzofuran-2-yl) acetate analogues (Choi et al., 2009a,b), we report the crystal structure of the title compound (Fig. 1).
The benzofuran unit is essentially planar, with a mean deviation of 0.008 (1) Å from the least-squares plane defined by the nine constituent atoms. The crystal packing ( Fig. 2) is stabilized by three intermolecular non-classical C-H···O hydrogen bonds; the first between an H atom of the benzofuran ring and the oxygen of the C═O unit, with a C5-H5···O3 i , the second between an H atom of the benzofuran ring and the oxygen of the isopropoxy group, with a C6-H6···O2 ii , the third between a methylene H atom and the oxygen of the S═O unit, with a C9-H9B···O4 iii , respectively (Table 1). The crystal packing ( Fig. 2) is further stabilized by aromatic π···π interactions between the benzene rings of neighboring molecules, with a Cg···Cg i distance of 3.688 (2) Å (Cg is the centroid of the C2-C7 benzene ring).

Experimental
77% 3-chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of isopropyl 2-(5fluoro-3-methylsulfanyl-1-benzofuran-2-yl) acetate (282 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 83%, m.p. 391-392 K; R f = 0.67 (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. Spectroscopic analysis: EI-MS 298 [M + ].

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 methine, 0.98 Å for the methylene, and 0.96 Å for the methyl H atoms. U iso (H) = 1.2U eq (C) for the aryl, methine, and methylene H atoms, and 1.5U eq (C) for the 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.