New synthetic method to 1,2-benzisothiazoline-3-one-1,1-dioxides and 1,2-benzisothiazoline-3-one-1-oxides from N-alkyl(o-methyl)arenesulfonamides

Various N-alkylsaccharins were easily prepared in moderate to good yields by the reaction of N-alkyl(o-methyl)arenesulfonamides with (diacetoxyiodo)benzene in the presence of iodine under irradiation with a tungsten lamp (W-h nu). On the other hand, irradiation of N-alkyl](o-methyl)arenesulfonamide derivatives bearing various substituents on the aromatic ring with a high-pressure mercury lamp (Hg-h nu), in the presence of (diacetoxyiodo)benzene and iodine gave the corresponding N-alkyl-1,2-benzisothiazoline-3-one-1-oxide derivatives in moderate yields, together with N-alkyl-1,2-benzisothiazoline-3-one-1,1-dioxide (saccharin) derivatives. (C) 1999 Elsevier Science Ltd. All rights reserved.