Methyl 2-[5-(4-hydroxyphenyl)-3-methylsulfanyl-1-benzofuran-2-yl]acetate

In the title compound, C18H16O4S, the 4-hydroxyphenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 34.52 (6)°. The methyl group of the methylsulfanyl substituent is almost perpendicular to the plane of the benzofuran fragment [100.90 (8)°] and is slightly tilted towards it. The crystal structure is stabilized by intermolecular O—H⋯O hydrogen bonds, and by intermolecular C—H⋯π interactions between a methyl H atom of the methylsulfanyl substituent and the 4-hydroxyphenyl ring.

In the title compound, C 18 H 16 O 4 S, the 4-hydroxyphenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 34.52 (6) . The methyl group of the methylsulfanyl substituent is almost perpendicular to the plane of the benzofuran fragment [100.90 (8) ] and is slightly tilted towards it. The crystal structure is stabilized by intermolecular O-HÁ Á ÁO hydrogen bonds, and by intermolecular C-HÁ Á Á interactions between a methyl H atom of the methylsulfanyl substituent and the 4-hydroxyphenyl ring.
The benzofuran unit is essentially planar, with a mean deviation of 0.005 (1) Å from the least-squares plane defined by the nine constituent atoms. The 4-hydroxyphenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 34.52 (6) Table 1). The crystal packing (Fig. 2) is further stabilized by intermolecular C-H···π interactions between the methyl H atom of the methylsulfanyl substituent and the 4-hydroxyphenyl ring, with a C18-H18C···Cg ii (Table 1; Cg is the centroid of the C12-C17 phenyl ring).
Experimental 2-[5-(4-Hydroxyphenyl)-3-methylsulfanyl-1-benzofuran-2-yl]acetic acid (471 mg, 1.5 mmol) was added to a solution of concentrated sulfuric acid (3 drops) in methanol (20 ml), and the mixture was refluxed for 6h, then cooled. The solvent was evaporated and the residue was poured into water. The mixture was extracted with dichloromethane, dried over magnesium sulfate, filtered and concentrated under vacuum. The residue was purified by column chromatography (benzene-acetone, 9 : 1 v/v) to afford the title compound as a colorless solid [yield 88%, m.p. 446-447 K; R f = 0.49 (benzene-acetone, 9 : 1 v/v)]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in benzene at room temperature.

Refinement
The hydroxy H atom was found in a difference Fourier map and refined freely. The other H atoms were positioned geometrically 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.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 0.69956 (