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 5, and by subsequent acidification the reaction product was converted into 4-methoxy-1,2-benzoisothiazol-3(2H)-one-1,1-dioxide. The obtained compound, together with 650 mg (10 mmols) of potassium cyanide in dimethyl-sulfoxide, was heated at 180° C. for 3 hours. After addition of petroleum ether the potassium salt of the product was precipitated, and the precipitate was dissolved in water. After acidifying with aqueous hydrochloric acid, filtering and recrystallizing, 1.46 gm (62% of theory) of 4-hydroxy-1,2-benzoisothiazol-3(2H)-one-1,1-dioxide were obtained.

1. customwas precipitated
2. dissolutionthe precipitate was dissolved in water
3. filtrationfiltering
4. customrecrystallizing