7-Bromo-2-methyl-1-tosylnaphtho[2,1-b]furan

The title compound, C20H15BrO3S, was prepared by the oxidation of 7-bromo-2-methyl-1-(4-tolylsulfanyl)naphtho[2,1-b]furan with 3-chloroperoxybenzoic acid. The 4-tolyl ring makes a dihedral angle of 70.96 (6)° with the plane of the naphthofuran fragment. The crystal structure is stabilized by aromatic π–π stacking interactions, with centroid–centroid distances of 3.672 (3) and 3.858 (3) Å between the central benzene and furan rings, and between the brominated benzene and central benzene rings of the naphthofuran system of neighbouring molecules, respectively. In addition, the stacked molecules exhibit C—H⋯π and inter- and intramolecular C—H⋯O interactions.

The title compound, C 20 H 15 BrO 3 S, was prepared by the oxidation of 7-bromo-2-methyl-1-(4-tolylsulfanyl)naphtho-[2,1-b]furan with 3-chloroperoxybenzoic acid. The 4-tolyl ring makes a dihedral angle of 70.96 (6) with the plane of the naphthofuran fragment. The crystal structure is stabilized by aromaticstacking interactions, with centroid-centroid distances of 3.672 (3) and 3.858 (3) Å between the central benzene and furan rings, and between the brominated benzene and central benzene rings of the naphthofuran system of neighbouring molecules, respectively. In addition, the stacked molecules exhibit C-HÁ Á Á and inter-and intramolecular C-HÁ Á ÁO interactions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2569).  Table 1; Cg1 is the centroid of the C13-C18 phenyl ring; symmetry code as in Fig. 2). Additionally, inter-and intramolecular C-H···O interactions in the structure were observed ( Fig. 2 and Table 1; symmetry code as in Fig. 2).

7-Bromo
Experimental 3-Chloroperoxybenzoic acid (77%, 377 mg, 1.68 mmol) was added in small portions to a stirred solution of 7-bromo-2methyl-1-(4-tolylsulfanyl)naphtho[2,1-b]furan (306 mg, 0.8 mmol) in dichloromethane (30 ml) at 273 K. After being stirred at room temperature for 4 h, 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 (chloroform) to afford the title compound as a colourless solid [yield 79%, m.p. 480-481 K; R f = 0.51 (chloroform)]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in chloroform at room temperature.

Refinement
All H atoms were geometrically positioned and refined using a riding model, with C-H = 0.95 Å for aromatic H atoms, 0.98 Å for methyl H atoms, respectively, and with U iso (H) = 1.2U eq (C) for aromatic H atoms and 1.5U eq (C) for methyl H atoms. The highest peak in the difference map is 0.77 Å from Br and the largest hole is 0.67 Å from Br.

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.