| abstract |
A process for preparing 3-isopropy1-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide (I) or a salt of I, which comprises reacting anthranilic isopropylamide II, simultaneously with sulfur trioxide or chlorosulfonic acid in the presence of an organic base or with adducts of sulfur trioxide and organic bases and phosphorus oxychloride at from 50 DEG C to the reflux temperature, followed, if appropriate, by conversion into its salts, is described. |