3-(4-Fluorophenylsulfonyl)-2-methylnaphtho[1,2-b]furan

In the title compound, C19H13FO3S, the 4-fluorophenyl ring makes a dihedral angle of 68.59 (5)° with the mean plane of the naphthofuran fragment. In the crystal, molecules are linked by weak intermolecular C—H⋯O, C—H⋯F and C—H⋯π interactions. The crystal structure also exhibits aromatic π–π interactions between the central benzene and the outer benzene rings of neighbouring molecules [centroid–centroid distance = 3.650 (3) Å].

In the title compound, C 19 H 13 FO 3 S, the 4-fluorophenyl ring makes a dihedral angle of 68.59 (5) with the mean plane of the naphthofuran fragment. In the crystal, molecules are linked by weak intermolecular C-HÁ Á ÁO, C-HÁ Á ÁF and C-HÁ Á Á interactions. The crystal structure also exhibits aromatic interactions between the central benzene and the outer benzene rings of neighbouring molecules [centroid-centroid distance = 3.650 (3) Å ].
In the title molecule ( Fig. 1), the naphthofuran unit is essentially planar, with a mean deviation of 0.008 (2) Å from the least-squares plane defined by the thirteen constituent atoms. The dihedral angle formed by the mean plane of the naphthofuran ring and the 4-fluorophenyl ring is 68.59 (5)°. The crystal packing ( Fig. 2) is stabilized by weak intermolecular C-H···O and C-H···F hydrogen bonds; the first one between a benzene H atom and the oxygen of the O═S═O unit (Table   1; C8-H8···O3 i ), and the second one between the 4-fluorophenyl H atom and the oxygen of the O═S═O unit (Table 1; C16-H16···O3 iii ), and the third one between the 4-fluorophenyl H atom and the fluorine (Table 1; C15-H15···F1 ii ). The crystal packing (Fig. 3) is also exhibits an intermolecular C-H..π interaction between a benzene H atom and the 4-fluorophenyl ring (Table 1; C4-H4···Cg1 iv , Cg1 is the centroid of the C14-C19 4-fluorophenyl ring). The crystal packing (Fig. 3) is further stabilized by an aromatic π-π interaction between the central benzene and the outer benzene rings of neighbouring molecules. The Cg2···Cg3 viii distance is 3.650 (3) Å (Cg2 and Cg3 are the centroids of the C2/C3/C4/C5/C10/C11 benzene ring and the C5-C10 benzene ring, respectively).

Experimental
77% 3-chloroperoxybenzoic acid (493 mg, 2.2 mmol) was added in small portions to a stirred solution of 3-(4-fluorophenylsulfanyl)-2-methylnaphtho [1,2-b]furan (339 mg, 1.1 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 8h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated at reduced pressure. The residue was purified by column chromatography (hexane-ethyl acetate, 4:1 v/v) to afford the title compound as a colorless solid [yield 71%, m.p. 439-440 K; Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the title compound in acetone at room temperature.

Refinement
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.

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.