Method for preparing 6-fluoro-3-(4- piperidyl)-1,2-benzo isoxazole hydrochlorate

The invention relates to a method for preparing a hydrochloride of 6-Fluoro-3-(4-piperidinyl)-1,2-benzisoxazole. The method is to subject 2,4-difluorophenyl(4-piperidinyl) ketoxime or a hydrochloride thereof to cyclopropanation and salifying in an aprotic solvent containing an alkali metal hydroxdide, wherein the molar ratio of the 2,4-difluorophenyl(4-piperidinyl) ketoxime or a hydrochloride thereof to the alkali metal hydroxide is 1 to between 1 and 3. The method can effectively prevent F atoms on para positions from participating in the reaction and avoid the production of a dipolymer (V), thereby avoiding the production of a dipolymer (VI) during the following preparation of risperidone. The method crystallizes crystals of a target substance directly by salifying, thereby solving theproblems of use of a plurality of kinds of organic solvents, complex operation and low yield due to the extraction by toluene, condensation, and crystallization of petroleum ether. The yield rate of the target substance is more than 80 percent, and the purity of target substance is more than 99 percent.