3-Alkylamino- and 3-arylamino isothiazole dioxides unsubstituted at C-4 and C-5 were synthesized starting from dithiopropionic amides. Taking advantage of the direct chlorination during the cyclization process or realizing an addition–elimination process with bromine on the final 3-aminoisothiazole dioxide derivatives, the corresponding 5-chloro-, 4,5-dichloro- or the 4-bromoisothiazole dioxides could