2-[(Methylsulfanyl)methyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide

In the title molecule, C9H9NO3S2, the essentially planar benzisothiazole ring system and the C—S—C atoms of the methylsulfanyl side chain form an angle of 64.45 (7)°. The structure is devoid of any classical hydrogen bonding. However, weak non-classical inter- and intramolecular hydrogen bonds of the type C—H⋯O are present.

In the title molecule, C 9 H 9 NO 3 S 2 , the essentially planar benzisothiazole ring system and the C-S-C atoms of the methylsulfanyl side chain form an angle of 64.45 (7) . The structure is devoid of any classical hydrogen bonding. However, weak non-classical inter-and intramolecular hydrogen bonds of the type C-HÁ Á ÁO are present.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH2683).  1,2-benzisothiazole-3-one 1,1-dioxide (saccharin) has been identified as an important molecular component in various classes of 5-HTla antagonists, analgesics and human mast cell tryptase inhibitors (Liang et al., 2006). Particularly, the substituted derivatives with e.g. N-hydroxy and N-alkyl substutuents have shown important biological activities (Nagasawa et al., 1995). Various biologically important saccharin skeletons and their N-alkyl derivatives were efficiently prepared (Xu et al., 2006) by chromium oxide-catalyzed oxidation of N-alkyl(o-methyl)arenesulfonamides in acetonitrile besides the already developed methodology utilizing irradiation techniques (Masashi et al., 1999) for similar type of conversions. In continuation of our research program on the synthesis of benzisothiazole derivatives (Siddiqui et al., 2007a(Siddiqui et al., ,b,2008a, we report the synthesis (see Fig. 3) and crystal structure of the title compound, in this paper.
In the molecular structure ( Fig. 1) the benzisothiazole rings system is essentially planar, the maximum deviation of any atom from the mean plane through S1/N1/C1-C7 being 0.0224 (8) Å for atom S1. The side chain comprising of atoms S2/C8/C9 is inclined at an angle 64.45 (7)° with the mean-plane of the benzisothiazole rings system. The structure is devoid of any classical hydrogen bonding. However, non-classical intermolecular hydrogen bond of the type C-H···O are present resulting in dimeric units in an R 2 2 (8) motif (Bernstein et al., 1994). In addition, intramolecular hydrogen bonds of the type C-H···O are also present in the structure resulting in an S(7) pattern (Bernstein et al., 1994) (details are in Fig. 2 and Table 1).

Experimental
A suspension of saccharin (I) (1.0 g, 5.46 mmol), sodium sulfite (1.4 g, 10.93 mmol) and an excess of 2-chloro-5-methylaniline (5 ml) was first stirred at room temperature (30 min.) and then under reflux (1.5 hrs). The reaction mixture turned orange red after reflux. Cooled the reaction mixture to room temperature and extracted the product with chloroform (3 X 25 ml). Concentrated the organic layer under reduced pressure (11 torr) to get light yellow product (II) (0.6 g, 2.46 mmol), yield = 45%. Recrystallization Solvent: MeOH:CH 3 CN (1:1). The solution was subjected to slow evaporation at 313 K to obtain colorless crystals.

Refinement
Though all the H atoms could be distinguished in the difference Fourier map the H-atoms were included at geometrically idealized positions and refined in riding-model approximation with the following constraints: aryl, methyl and methylene C-H distances were set to 0.95, 0.98 and 0.99 Å, respectively; in all these instances U iso (H) = 1.2 U eq (C). The final difference map was free of any chemically significant features.
supplementary materials sup-2 Figures   Fig. 1. ORTEP-3 (Farrugia, 1997) drawing of the title compound with displacement ellipsoids plotted at 50% probability level.   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.