(E)-N,N′-Bis[2-(5-bromo-1H-indol-3-yl)ethyl]-N,N′-(but-2-ene-1,4-diyl)bis(4-methylbenzenesulfonamide)

In the title compound, C38H38Br2N4O4S2, there is a crystallographic inversion center located at the mid-point of the alkene bond. The dihedral angle between the aromatic ring systems in the asymmetric unit is 87.69 (19)°. In the crystal, adjacent molecules are linked by pairs of N—H⋯O hydrogen bonds, generating R 2 2(16) loops within [10] chains. Short Br⋯Br contacts [3.6148 (9) Å] are observed between adjacent molecules.

In the title compound, C 38 H 38 Br 2 N 4 O 4 S 2 , there is a crystallographic inversion center located at the mid-point of the alkene bond. The dihedral angle between the aromatic ring systems in the asymmetric unit is 87.69 (19) . In the crystal, adjacent molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, generating R 2 2 (16) loops within [110] chains. Short BrÁ Á ÁBr contacts [3.6148 (9) Å ] are observed between adjacent molecules.   Table 1 Hydrogen-bond geometry (Å , ).
Sulfonamides exhibit a broad area of biological activites (e.g. Ozbek et al., 2007). As part of our studies in this area, we now describe the stucture of the title compound, (I) (Fig. 1). For related structures, see: Abbassi et al.(2011);Akkurt et al.. (2011).
In the title molecule the S atom has a distorted tetrahedral geometry [maximum deviation: O1-S1-O2 =119.82 (19)°] which is possible due to the two S=O double bonds electron repulsion. In the crystal structure, the molecules are linked by four N-H···O hydrogen bonds with adjacent molecules. There also exists weak Br···Br Van der waals interaction to link adjacent molecules.

Experimental
A solution of 5-bromo tryptamine 1 in (6.68 g, 28.1 mmol) in dichloromethane (100 ml) was cooled in an ice bath, then triethyl amine (8.51 g, 84.3 mmol) and p-toluenesulfonyl chloride (5.90 g, 30.9 mmol) were added. The mixture was stirred for 30 min, successively washed with water, brine and dried over MgSO 4 . The solvent was removed in high vacuum, and the tosyl protected tryptamine 2 was obtained in 95% yield (8.38 g, 26.7 mmol) by flash chromatography.
A three-necked flask was charged with tosyl protected tryptamine 2 (8.38 g, 26.7 mmol), acetone (60 ml) and water (60 ml). Then sodium hydroxide (1.60 g, 40.1 mmol) was added. After the solid was dissolved, allyl bromide (3.52 g, 29.4 mmol) was added slowly. The mixture was stirred overnight and evaporated under reduced pressure to remove acetone. The aqueous layer was extracted with CH 2 Cl 2 (3 × 50 ml). The combined organic phase was washed with brine, separated, dried over Na 2 SO 4 , filtrated, and evaporated under reduced pressure. The residue was purified by recrystallization in ethyl acetate to afford the corresponding allyl indolyl compound 3 as a white solid in 84% yield (7.94 g, 22.4 mol).
A solution of 3 (2.00 g, 5.65 mmol) and methyl vinyl ketone (1.19 g, 16.95 mmol) in 1,2-dichloride ethane (40 ml) was heated to 60 ?, then ruthenium catalyst Zhan-1B (83 mg, 0.113 mmol) was added in one portion. The mixture was stirred for 2 days and evaporated under reduced pressure. The residue was purified by flash chromatography to afford compound 4 in 13% yield (615 mg, 0.73 mmol). Colourless blocks of (I) were grown from ethyl acetate and petroleum solution.

Refinement
The H atom was placed onto the N atom in indol ring in a calculated positions with N-H = 0.86Å with U iso (H) = 1.2Ueq(N).
The remaining H atoms were placed in a calculated positions with C-H = 0.93-0.97Å and were included in the final cycle of refinement in riding mode with U iso (H) = 1.2 or 1.5Ueq(C).