Benzene-1,3,5-triyl tris(methanesulfonate)

In the molecule of the title compound, C9H12O9S3, the two methanesulfonate groups re located one above and one below the ring plane. The C—O—S angle range is 119.3 (2)–121.1 (2)°. This conformation is different from that of the benzene analog 1,2,5-tris(p-toluenesulfonate), which is a three-legged ‘table’ with all fragments of the p-toluenesulfonate on top of the benzene ring. In the crystal, the supramolecular aggregation is completed by the presence of C—H⋯O hydrogen bonds.

In the molecule of the title compound, C 9 H 12 O 9 S 3 , the two methanesulfonate groups re located one above and one below the ring plane. The C-O-S angle range is 119.3 (2)-121.1 (2) . This conformation is different from that of the benzene analog 1,2,5-tris(p-toluenesulfonate), which is a three-legged 'table' with all fragments of the p-toluenesulfonate on top of the benzene ring. In the crystal, the supramolecular aggregation is completed by the presence of C-HÁ Á ÁO hydrogen bonds.

Comment
The synthesis of supported organic compounds and dendrimers on Merrifield resin with a mesyl group and a trihydroxybenzene core has been one of our objectives; however the analysis of the supported products on the solid state is only limited to infrared spectroscopy (Grice et al., 2000;Yan et al., 2001). In our previous work we have used mass spectroscopy to characterize intermediates and products (Chavez et al., 2003;Olivas et al., 2008;. Madrigal et al., 2006). In this work, and as part of our ongoing research, we have synthesized benzene-1,3,5-triyl trimethanesulfonate using 1,3,5 trihydroxybenzene.
The product (I) is an intermediate in the synthesis of complex first , second and third generation dendrimers.
As shown in Fig. 1, the molecule shows two fragments of trimethanesulfonate above and one below the plane of the benzene ring, with angles C5-O3-S2 119.3 (2)° , C1-01-S1 121.1 (2)° and C3-02-S3 120.2 (2)°. This conformation is different from the one shown by the analogue benzene 1,2,5-tris(p-toluenesulfonate), where the conformation of the molecule is described as a three-legged table (all fragments of the p-toluenesulfonate lay on the top of the benzene ring) stabilized by intramolecular C-H···O and C-H···π (Vembu et al., 2003).

Experimental
The synthesis of the title compound included reagents and solvents of reagent grade, which were used without further purification. In a round bottom flask of 10 ml provided with a magnetic stirrer, was placed 0.3 g (2.3 mmol) of 1,3,5-trihydroxybenzene and 3 ml of pyridine. The flask was immersed in an ice bath and 0.58 ml (7.6 mmol) of methanesulfonyl chloride was added dropwise. The mixture was stirred for one hour and stored in the refrigerator for 24 hours. The reaction mixture was poured on to cracked ice and the precipitate was washed with a cold solution 20% of HCl (3 x 5 ml) and cold water Crystallization. 50 mg of benzene-1,3,5-triyl trimethanesulfonate compound was placed in a glass vial and 3 ml of dimethyl sulfoxide was added. The solution was allowed to stand at room temperature for seven days and the crystals formed were separated by filtration.  Fig. 1. The title compound (I) with displacement ellipsoids drawn at a 30% probability level.

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 > σ(F 2 ) is used only for calculating Rfactors(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.