Crystal structure of N,N-dimethyl-2-[(4-methylbenzyl)sulfonyl]ethanamine

The title compound has a disordered structure with two equally populated conformations of the amine fragment. A pair of weak C—H⋯O intermolecular interactions between the CH2 and SO2 groups gives a one-dimensional supramolecular structure running along the a-axis direction.


Chemical context
Parasitic helminths possess a number of evolutionary strategies that facilitate their co-existence with their host and, as such, up to one third of the global population may suffer from helminthetic infections (de Silva et al., 2003). These parasites can secrete immunomodulatory molecules that prevent the parasites' clearance from the host without leaving the host vulnerable to opportunistic infections (Hewitson et al., 2009). ES-62 is one such immunomodulatory molecule, a protein, which was discovered in the secretions of the rodent filarial nematode Acanthocheilonema and demonstrated to induce an anti-inflammatory immunological phenotype (Harnett et al., 1989). ES-62 has been studied for its potential to treat human diseases relating to inflammation, for example collageninduced arthritis or rheumatoid arthritis, and many positive outcomes have been demonstrated.
A number of the significant anti-inflammatory activities of ES-62 are associated with post-translational glycosylation and subsequent esterification by phosphorylcholine. However, ES-62 is an immunogenic protein and is thus unsuitable as a drug itself (Harnett & Harnett, 2009). We have sought to capitalize on the immunomodulatory effects of ES-62 whilst avoiding its inherent undrugability through synthesizing a library of druglike small molecules based upon phosphorylcholine, the active moiety of ES-62. A series of sulfone analogues ( Fig. 1) have proven to be of great significance in our investigations into General structure of sulfone analogues. R represents alkyl chains and X represents halogen substituents. collagen-induced arthritis. Despite the apparent simplicity of these molecules, we are aware of no relevant crystallographic study. As such, and as the title compound is of particular interest to our ongoing work (Al-Riyami et al., 2013), we report herein on the solid-state structure of the title compound.

Structural commentary
The molecular structure of the title compound is shown in Fig. 2. The amine group is disordered over two equally occupied sites such that the lone pair of the pyramidal N atom is anti to O1 with respect to the plane defined by C1-S1-C9 for the conformer containing N1 but syn for the N1A conformer.

Supramolecular features
Neighbouring molecules related by translation along the aaxis direction are connected by two weak C-HÁ Á ÁO hydrogen bonds involving O1 and C1 and C9/C9A (Table 1 and Fig. 3). This gives one-dimensional supramolecular chains of mol-ecules that propagate parallel to the crystallographic a-axis direction.
Other close interactions involve the disordered fragment. Thus the methyl group of C11A approaches the aromatic ring, giving a C-ċ interaction [closest contact C6Á Á ÁC11A = 3.345 (5) Å ] whilst C11 forms unfeasibly short intermolecular interactions with its centrosymmetrically related self -an interaction that is relieved by the observed disorder.

Synthesis and crystallization
A mixture of 2-[(4-methylbenzyl)sulfonyl]ethyl methanesulfonate and 1-methyl-4-[(vinylsulfonyl)methyl]benzene (4.880 g) was dissolved in dichloromethane (50 ml, dry) to which dimethylamine (4 ml, 2M in THF) was added at room temperature with stirring. The stirring was continued at room temperature overnight. The reaction mixture was extracted with a saturated solution of sodium carbonate. The organic layer was collected, dried over MgSO 4 , filtered and the solvents were removed under reduced pressure and the crude product was applied to a silica gel column chromatography using first ethyl acetate/n-hexane (1/1, RF = 0.1) and then ethyl acetate/methanol (9/1). The product was obtained as a white solid which was recrystallized from ethyl acetate/nhexane ( Table 1 Hydrogen-bond geometry (Å , ). Symmetry code: (i) x À 1; y; z.

Figure 2
The molecular structure of the title compound with non-H atoms shown as 50% probability displacement ellipsoids. For the disordered fragment, the atoms labelled with the suffix 'a' have been shown with hollow bonds whilst all other bonds are shown as solid lines.

Figure 3
Part of the molecular chain formed by translation along a highlighting the C-HÁ Á ÁO contacts. Only one of the two disordered conformations is shown.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Models where the site occupancy factors of the disordered groups were allowed to refine gave occupancies equal to 50%. So in the final model, occupancies of all the disordered atoms were set to this value. The C9-C10 and C9A-C10A distances were restrained to be 1.53 (1) Å . All H atoms were placed in idealized positions and were refined in riding modes with C-H equal to 0.95, 0.98 and 0.99 Å for CH, CH 2 and CH 3 groups, respectively, and U iso (H) = 1.5U eq (C) for methyl groups and 1.2U eq (C) for all other groups.   (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).   7, 130.8, 129.0, 125.4, 58.4, 51.6, 49.0, 44.9, 20.7. IR (KBr): 1511, 1463, 1399, 1380, 1314, 1258, 1156, 1119, 1050, 749 cm -1 . Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.