Patent ID: 6252069
Filing Date: 2001-06-26
Classification: C07D

Abstract:
A process for preparing 3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (I) ##STR6##or a salt of (I) by reacting anthranilic isopropylamide (II) ##STR7##with a sulfur trioxide component selected from the group ofa) sulfur trioxide or chlorosulfonic acid and an organic base, andb) an adduct of sulfur trioxide and an organic base, and with phosphorus oxytrichloride, which process comprises simultaneously contacting (II), at a temperature of from 50.degree. C. to reflux temperature, with the sulfur trioxide component and with the phosphorus oxytrichloride to give (I), and optionally subsequently reacting (I) with an inorganic base to give the salt of (I).