Crystal structure of (E)-N-{2-[2-(4-methylbenzylidene)hydrazin-1-yl]-2-oxoethyl}-p-toluenesulfonamide

The title compound, an arylsulfonyl glycinyl aryl hydrazone Schiff base, crystallizes with two independent molecules in the asymmetric unit. In the crystal, a series of N—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π and slipped parallel π–π interactions link the molecules, forming a three-dimensional structure.

The title acylhydrazone derivative, C 17 H 19 N 3 O 3 S, containing an amino acid moiety and electron-donating substituents attached to both the phenyl rings, crystallized with two independent molecules (A and B) in the asymmetric unit. The molecules are bent at the S atom, with C-SO 2 -NH-CH 2 torsion angles of À67.3 (2) and 67.7 (3) in molecules A and B, respectively. Further, the dihedral angles between the sulfonylglycine segments and the p-toluenesulfonyl rings are 76.1 (1) and 85.8 (1) in molecules A and B, respectively. The central hydrazone segments and the toluene rings attached to them are almost co-planar with their mean planes being inclined to one another by 5.2 (2) (molecule A) and 2.9 (2) (molecule B). The dihedral angles between the benzene rings are 86.83 (12) (molecule A) and 74.00 (14) (molecule B). In the crystal, the A molecules are linked by a pair of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (8) ring motif. The dimers are linked via three N-HÁ Á ÁO hydrogen bonds involving the B molecules, forming chains along [100] and enclosing R 2 2 (12) and R 4 4 (16) ring motifs. The chains are linked via C-HÁ Á ÁO hydrogen bonds and a C-HÁ Á Á interaction, forming sheets parallel to (010). There is a further C-HÁ Á Á interaction and a slipped parallelinteraction [inter-centroid distance = 3.8773 (16) Å ] between the sheets, leading to the formation of a three-dimensional framework.

Chemical context
Hydrazones display numerous biological activities. The hydrazone Schiff bases of aroyl, acyl and heteroaroyl compounds are more versatile and flexible (in the sense that they can be used as reaction intermediates in organic synthesis and as ligands forming complexes with metal ions in coordination chemistry) due to the presence of the C O group, an additional donor site. N-acylhydrazones containing a glycine residue have been investigated extensively for their biological and medical activities (Tian et al., 2011). Antiviral activity has been shown for acylhydrazone derivatives which contain an amino acid moiety and an electron-donating substituent in the sulfonyl phenyl ring (Tian et al., 2009). The biological activities of these Schiff bases are thought to be related to structural aspects.
In a continuation of our studies of substituent effects on the structures of such compounds, for example N-(aryl)-amides Rodrigues et al., 2011), N-chloroarylamides (Jyothi & Gowda, 2004) and N-bromoarylsulfonamides (Usha & Gowda, 2006), we report herein on the synthesis and crystal structure of the title compound. This acylhydrazone derivative contains a glycine moiety and elec- ISSN 2056-9890 tron-donating substituents in both the sulfonyl and hydrazone aromatic rings.

Synthesis and crystallization
p-Toluenesulfonyl chloride (0.01 mol) was added to glycine (0.02 mol) dissolved in an aqueous solution of potassium carbonate (0.06 mol, 50 ml). The reaction mixture was stirred at 373 K for 6 h, left overnight at room temperature, then filtered and treated with dilute hydrochloric acid. The solid N-(p-toluenesulfonyl)glycine (L1) obtained was crystallized from aqueous ethanol. Sulfuric acid (0.5 ml) was added to L1 (0.02 mol) dissolved in ethanol (30 ml) and the mixture was refluxed. The reaction was monitored by TLC at regular intervals. After completion of the reaction, the reaction mixture was concentrated to remove the excess ethanol. The product, N-(p-toluenesulfonyl)glycine ethyl ester (L2) was poured into water, neutralized with sodium bicarbonate and recrystallized from acetone.
The pure L2 (0.01 mol) was then added in small portions to a stirred solution of 99% hydrazine hydrate (10 ml) in 30 ml ethanol and the mixture was refluxed for 6 h. After cooling to room temperature, the resulting precipitate was filtered, washed with cold water and dried to give N-(p-toluenesulfonyl)glycinyl hydrazide (L3).
A mixture of L3 (0.01 mol) and p-methylbenzaldehyde (0.01 mol) in anhydrous methanol (30 ml) and two drops of glacial acetic acid was refluxed for 8 h. After cooling, the precipitate was collected by vacuum filtration, washed with cold methanol and dried. It was recrystallized to constant Hydrogen-bonding pattern in the title compound (see Table 1 for details).

Figure 3
A view along the b axis of the crystal packing of the title compound. For details of the hydrogen bonds and C-HÁ Á Á interactions (dashed lines), see Table 1 (molecule A is blue and molecule B is red). melting point from methanol (455-457 K). Prism-like colourless single crystals were grown from a DMF solution by slow evaporation of the solvent. The purity of the compound was checked by TLC and characterized by its IR spectrum. The characteristic absorptions observed are 3286.7, 1678.1, 1606.7, 1323.2 and 1157.3 cm À1 for the stretching bands of N-H, C-O, C-N, S-O asymmetric and S-O symmetric, respectively.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The amino H atoms were located in difference Fourier maps and refined with distance restraints: N-H = 0.86 (2) Å with U iso (H) = 1.2U eq (N). The C-bound H atoms were positioned with idealized geometry and refined using a riding model: C-H = 0.93-0.97 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for other H atoms.  Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).