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 process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide, which comprises:
(a) reacting 4-hydroxycoumarin, hydroxylamine or an acid addition salt thereof, and a base in water to give a first mixture;
(b) acidifying the first mixture, adding 1,2-dichloroethane thereto to give a second mixture, and removing an aqueous layer from the second mixture to give a third mixture containing 1,2-benzisoxazole-3-acetic acid and 1,2-dichloroethane;
(c) removing water from the third mixture by distillation to give a fourth mixture, adding chlorosulfonic acid to the fourth mixture and reacting the mixture to give a fifth mixture, and adding a base to the fifth mixture to give a sixth mixture containing an alkali metal salt of 1,2-benzisoxazole-3-methanesulfonic acid;
(d) adding phosphoryl chloride to the sixth mixture, and reacting the mixture to give a seventh mixture containing 1,2-benzisoxazole-3-methanesulfonyl chloride;
(e) adding ammonia to the seventh mixture and reacting the mixture to give an eighth mixture containing 1,2-benzisoxazole-3-methanesulfonamide; and
(f) isolating the 1,2-benzisoxazole-3-methanesulfonamide.
2. A process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide according to claim 1 , wherein the reaction in (a) is conducted in the presence of a chelating agent to give the first mixture.
3. A process for the preparation of 1,2-benzisoxazole-3-methanesulfonamide according to claim 2 , which further comprises washing the first mixture with 1,2-dichloroethane before acidifying the first mixture in (b).
4. 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 a base thereto to give a second mixture containing an alkali metal salt of 1,2-benzisoxazole-3-methanesulfonic acid;
(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 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.
5. A process for the preparation of 1,2-benzisoxazole-3-acetic acid, which comprises reacting 4-hydroxycoumarin, hydroxylamine or an acid addition salt thereof, and a base in water, and acidifying the resulting reaction mixture.
6. A process for the preparation of 1,2-benzisoxazole-3-acetic acid according to claim 5 , wherein the reaction of 4-hydroxycoumarin, hydroxylamine or an acid addition salt thereof, and a base is conducted in the presence of a chelating agent.
7. A process for the preparation of 1,2-benzisoxazole-3-acetic acid according to claim 5 , which further comprises washing the reaction mixture of 4-hydroxycoumarin, hydroxylamine or an acid addition salt thereof, and a base with 1,2-dichloroethane before acidifying thereof.
8. A process for the preparation of 1,2-benzisoxazole-3-acetic acid according to claim 6 , which further comprises washing the reaction mixture of 4-hydroxycoumarin, hydroxylamine or an acid addition salt thereof, and a base with 1,2-dichloroethane before acidifying thereof.