Method for preparing benzisoxazole methane sulfonyl chloride and its amidation to form zonisamide

摘要

The present invention relates to a process of preparing benzisoxazole methane sulfonic acid-chloride (BOS-Cl) as an zonisamide intermediate via chlorination of benzisoxazole methane sulfonate. The present invention also discloses a process of preparing zonisamide via amidation of BOS-Cl. More particularly, the present invention provides a process of preparing zonisamide, comprising the steps of: a) chlorinating BOS, salts or esters thereof, with SOCl₂ in an organic solvent and/or in the presence of a catalyst to form BOS-Cl; and b) amidating BOS-Cl in the presence of ammonia selected from the group consisting of aqueous ammonia in a biphasic system, masked ammonia and dry ammonia to form zonisamide.