反应详情

2.5 gm (11.8 mmols) of 3-amino-4-methoxy-1,2-benzoisothiazole-1,1-dioxide were reacted with sodium hydroxide analogous to Example 4. The reaction mixture was acidified, whereby 4-methoxy-1,2-benzoisothiazol-3(2H)-one-1,1-dioxide was obtained, which was subsequently heated at 200°-205° C. with 20 gm of pyridine hydrochloride. After cooling, the reaction mixture was extracted several times with boiling benzene, the residue was dissolved in water, and the aqueous solution was again extracted with boiling benzene. The combined benzene phases were dried and evaporated in vacuo. The residue was recrystallized from water, yielding 1.35 gm (57.5% of theory) of 4-hydroxy-1,2-benzoisothiazol-3(2H)-one-1,1-dioxide.