IMPROVED PROCESS FOR THE PREPARATION OF INTERMEDIATES USEFUL FOR THE PREPARATION OF ZONISAMIDE

摘要

The invention relates to an improved process for the preparation of 1,2-benzisoxazole-3­-methane sulfonates and a novel compound 4-oximino-2,3-dihydrobenzoxathiin-2, 2­-dioxides. The 1,2-benzisoxazole-2-methane sulfonates and 4-oximino-2, 3-­dihydrobenzoxathiin-2, 2-dioxides prepared by the processes of the present invention have the general formula (2) & (3) respectively . The compounds of the formulae (2) and (3) are important intermediates for the preparation of Zonisamide of the formula (1) (an anticonvulsant drug). The compounds of the formula (2) is prepared from hitherto unknown compound 4-oximino-2,3-dihydrobenzoxathiin-2, 2-dioxides of the formula (3) using strong bases with suitable solvents. The novel compounds of the formula (3) is prepared by the intramolecular Cyclocondensation of the compound of the formula (4) to get the compound of the formula (5) and subsequent reaction with hydroxylamine hydrochloride to get the novel intermediates of the formula (3). In the above mentioned formulae R1 to R4 - may be the same or different and represents hydrogen, alkyl, (with carbons, 2-5), chloro, bromo, S- alkyl, o- alkyl, NO2, N- Me2, CF3. and where X represents Na or K.