(S)-N-[1-(5-Benzylsulfanyl-1,3,4-oxadiazol-2-yl)-2-phenylethyl]-4-methylbenzenesulfonamide

The title compound, C24H23N3O3S2, crystallizes with two independent molecules in the asymmetric unit. They differ essentially in the orientation of the tolyl rings, between which there is π–π stacking (centroid–centroid distance = 3.01 Å). The absolute configuration was confirmed by the determination of the Flack parameter [x = 0.008 (9)]. In the crystal, molecules are connected by two classical N—H⋯N hydrogen bonds and two weak but very short C—H⋯Osulfonyl interactions, forming layers lying parallel to the bc plane.

The title compound, C 24 H 23 N 3 O 3 S 2 , crystallizes with two independent molecules in the asymmetric unit. They differ essentially in the orientation of the tolyl rings, between which there isstacking (centroid-centroid distance = 3.01 Å ). The absolute configuration was confirmed by the determination of the Flack parameter [x = 0.008 (9)]. In the crystal, molecules are connected by two classical N-HÁ Á ÁN hydrogen bonds and two weak but very short C-HÁ Á ÁO sulfonyl interactions, forming layers lying parallel to the bc plane.
anti-HIV and anti-HCV activities and herein we report on its crystal structure.
The molecular structure of the two independent molecules (1 and 2) of the enantiomerically pure title compound are shown in Fig. 1. The two molecules are related by a pseudo twofold axis. The main difference between the two molecules is the rotation of the tolyl group; the corresponding torsion angles are N5-S1-C14-C15 61.4 (2), and N5'-S1'-C14'-C15' 100.2 (2)°. A least-squares fit of both molecules, ignoring atoms (C15-C20), gave an r.m.s. deviation of 0.19 Å (Fig. 2). The large number of single bonds means that the molecules have a considerable number of torsional degrees of freedom. The conformation actually adopted is a flattened form in which all rings are arranged to correspond approximately to the smallest dimension of the molecular "box". This was calculated, [RPLUTO;CCDC, 2007], to be 7.9Å for molecule 1 and 7.7 Å for molecule 2.
In the crystal of the title compound, the molecular packing is largely determined by two short classical N-H···N hydrogen bonds, together with two "weak" but very short C-H···O sulfonyl interactions (see Table 1 for details). The combinaton of these interactions leads to the formation of layers lying parallel to the bc plane (Fig. 3).

Experimental
The synthesis and spectral data of the compound under study have been described previously by our laboratory (Syed et al., 2011a).