Patent ID: 7262304

Claim:
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.