1-Ethylsulfinyl-2-(4-iodophenyl)naphtho[2,1-b]furan

In the title compound, C20H15IO2S, the 4-iodophenyl ring makes a dihedral angle of 44.21 (7)° with the plane of the naphthofuran fragment. In the crystal, molecules are linked by weak intermolecular C—H⋯O and C—H⋯π interactions.

In the title compound, C 20 H 15 IO 2 S, the 4-iodophenyl ring makes a dihedral angle of 44.21 (7) with the plane of the naphthofuran fragment. In the crystal, molecules are linked by weak intermolecular C-HÁ Á ÁO and C-HÁ Á Á interactions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: DS2042).
The naphthofuran unit is essentially planar, with a mean deviation of 0.044 (2) Å from the least-squares plane defined by the thirteen constituent atoms. The dihedral angle formed by the naphthofuran plane and the 4-iodophenyl ring is 44.21 (7)°.
The crystal packing (Fig. 2) is stabilized by a weak intermolecular C-H···O hydrogen bond between the methyl H atom of the ethyl group and the oxygen of the S═O unit, with a C20-H20C···O2 i ( Table 1). The molecular packing ( Fig. 2) is further stabilized by an intermolecular C-H···π interaction between the methylene H atom of the ethyl group and the 4-iodophenyl ring of an adjacent molecule, with a C19-H19B···Cg ii (Table 1; Cg is the centroid of the C13-C18 4-iodophenyl ring).

Experimental
77% 3-chloroperoxybenzoic acid (157 mg, 0.7 mmol) was added in small portions to a stirred solution of 1-ethylsulfanyl-2-(4-iodophenyl)naphtho [2,1-b]furan (301 mg, 0.7 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 5h, 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, 2:1 v/v) to afford the title compound as a colorless solid [yield 74%, m.p. 440-441 K; R f = 0.53 (hexane-ethyl acetate, 2:1 v/v)]. Single crystals suitable for X-ray diffraction were prepared 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, 0.99 Å for methylene, and 0.98 Å for methyl H atoms. U iso (H) = 1.2U eq (C) for aryl and methylene H atoms, 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.