5-(4-Fluorophenyl)-3-methylsulfanyl-2-phenyl-1-benzofuran

In the title compound, C21H15FOS, the dihedral angle between the mean plane of the benzofuran fragment and the mean planes of the pendant 4-fluorobenzene and phenyl rings are 31.72 (6)° and 32.51 (6)°, respectively. In the crystal, the molecules are linked by weak C—H⋯π interactions. The crystal studied was a merohedral twin with a 0.62 (9):0.38 (9) domain ratio.

In the title compound, C 21 H 15 FOS, the dihedral angle between the mean plane of the benzofuran fragment and the mean planes of the pendant 4-fluorobenzene and phenyl rings are 31.72 (6) and 32.51 (6) , respectively. In the crystal, the molecules are linked by weak C-HÁ Á Á interactions. The crystal studied was a merohedral twin with a 0.62 (9):0.38 (9) domain ratio.
Cg is the centroid of the C15-C20 phenyl ring.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB6402). structure of the title compound.
The title compound crystallizes as the non-centrosymmetric space group P 21 in spite of having no asymmetric C atoms.
In the title molecule ( Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.006 (2) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle formed by the 4-fluorophenyl ring and the mean plane of the benzofurn fragment is 31.72 (6)°. The dihedral angle between the phenyl ring and the mean plane of the benzofurn fragment is 32.51 (6)°. The crystal packing (Fig. 2) is stabilized by intermolecular C-H···π interactions between a 4-fluorophenyl H atom and the phenyl ring (Table 1; C14-H14···Cg i , Cg is the centroid of the C15-C20 phenyl ring).

Experimental
Zinc chloride (273 mg, 2.0 mmol) was added to a stirred solution of 4-fluoro-4'-hydroxybiphenyl (376 mg, 2.0 mmol) and 2-chloro-2-methylsulfanylacetophenone (401 mg, 2.0 mmol) in dichloromethane (30 mL) at room temperature, and stirring was continued at the same temperature for 1 h. The reaction was quenched by the addition of water and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated at reduced pressure. The residue was purified by column chromatography (hexane-benzene, 5:2 v/v) to afford the title compound as a colorless solid [yield 61%, m.p. 415-416 K; R f = 0.78 (hexane-benzene, 5:2 v/v)]. Colourless blocks were prepared by slow evaporation of a solution of the title compound in carbon tetrachloride at room temperature.

Refinement
The reported Flack parameter was obtained by TWIN/BASF procedure in SHELXL (Sheldrick, 2008). All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aryl and 0.98 Å for methyl H atoms.
U iso (H) =1.2U eq (C) for aryl and 1.5U eq (C) for methyl H atoms.
supplementary materials sup-2 Figures Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are presented as small spheres 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.