4-Methyl-N-(3-oxo-2,3-dihydro-1,2-benzisothiazol-2-yl)benzenesulfonamide

In the title molecule, C14H12N2O3S2, the benzisothiazolone ring system is essentially planar and forms a dihedral angle of 67.37 (6)° with the plane of the benzene ring. In the crystal structure, molecules are linked via intermolecular N—H⋯O and C—H⋯O hydrogen bonds to form chains parallel to the b axis.

In the title molecule, C 14 H 12 N 2 O 3 S 2 , the benzisothiazolone ring system is essentially planar and forms a dihedral angle of 67.37 (6) with the plane of the benzene ring. In the crystal structure, molecules are linked via intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds to form chains parallel to the b axis.
Financial support from the Italian MIUR (Ministero dell'Istruzione, dell'Universitá e della Ricerca) is gratefully acknowledged.

Comment
Over the past decades a substantial number of 1,2-benzisothiazol-3(2H)-one derivatives have been reported to possess a wide range of biological activities including antimicrobial, antiviral, anticancer, anti-inflammatory, cartilage antidegenerative and other pharmacological activities (Clerici et al., 2007;Siegemund et al., 2002). As part of our program aimed at developing novel biologically active 1,2-benzisothiazol-3(2H)-ones, we have synthesized in the last years 2-amino-1,2-benzisothiazol-3(2H)-one derivatives resulted in the discovery of new compounds active as antiplatelet/spasmolitic agents (Vicini et al., 1997;Vicini et al., 2000) and of compounds endowed with very interesting antimicrobial properties (Vicini et al., 2002;Zani et al., 2004). Recently, in our continuing efforts to find novel effective 2-amino-1,2-benzisothiazol-3(2H)-one derivatives, we have synthesized a series of 2-(phenylsulfonyl)amino-1,2-benzisothiazol-3(2H)-ones which exhibit anti-HIV-1 activity against wild type virus and against viral strains carrying clinically relevant mutations (Vicini et al., 2009). Experimental evidences suggest non classical targets for this novel class of anti-HIV-1 agents. In order to study their binding sites at a molecular level we thought it appropriate to obtain X-ray crystallographic data for a prototype.

Experimental
The title compound was synthesized as described elsewhere (Vicini et al., 2009). Freshly prepared chlorocarbonylsulfenylchloride (18 mmol) in dried CCl 4 (40 ml) was added dropwise to a stirred, ice-cooled solution of 2-tosylhydrazine (20 mmol) in pyridine (18 ml). After 2 h the reaction mixture was allowed to cool to room temperature and the crude product was filtered, purified by base-acid (Na 2 CO 3 -HCl) exchange and silica-gel column chromatography (eluent CH 2 Cl 2 -EtOH 95:5 v/v). Pale yellow single crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution at room temperature.

Refinement
The H atoms bound to the N2 atom was located in a difference Fourier map and refined isotropically with the N-H distance constrained to 0.87 (1) Å. All other H atoms were placed at calculated positions and refined using a riding model, with C-H = 0.93-0.96 Å, and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms. Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.

Special details
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.