One-pot process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide
View Patent ↗A process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide without isolation of intermediates in solid form, by using 4-hydroxycoumarin as a starting compound, and water and 1,2-dichloroethane as solvents; and an industrially useful process for the preparation of 1,2-benzisoxazole-3-acetic acid, by reacting 4-hydroxycoumarin and hydroxylamine in water.
1. A one-pot process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide, which comprises:
(i) reacting 1,2-benzisoxazole-3-acetic acid and chlorosulfonic acid in 1,2-dichloroethane to give a first mixture, and adding sodium hydroxide thereto to give a second mixture containing sodium 1,2-benzisoxazole-3-methanesulfonate;
(ii) adding phosphoryl chloride to the second mixture, and reacting the mixture to give a third mixture containing 1,2-benzisoxazole-3-methanesulfonyl chloride;
(iii) adding ammonia gas to the third mixture and reacting the mixture to give a fourth mixture containing 1,2-benzisoxazole-3-methanesulfonamide; and
(iv) isolating the 1,2-benzisoxazole-3-methanesulfonamide, wherein all of (i) to (iii) are conducted in a single reactor without isolating intermediates in solid form.
2. The one-pot process according to claim 1 , wherein in step (i) is conducted in the presence of dioxane.
3. The one-pot process according to claim 1 , wherein in step (i) is conducted in the absence of dioxane.
4. The one-pot process according to claim 1 , wherein the reaction of 1,2-benzisoxazole-3-acetic acid with chlorosulfonic acid is conducted at a temperature in the range of 60° C. to 80° C.
5. The one-pot process according to claim 1 , wherein a tertiary amine is added to the second reaction mixture in step (ii).