| abstract |
A process for the preparation of 3-{2-[4-(6-fluorobenzo [d] isoxazol-3-yl)-piperidin-1-yl]-ethyl}-2-methyl-6,7,8,9-tetrahydro-4H-pyrido-[1,2-a] pyrimidin-4-one of formula (I) is disclosed, wherein the process comprises: condensation of (2-methyl-4-oxo- 6,7,8,9-tetrahydro-4H-pyrido-[1,2-a] pyrimidin-3-yl)- acetaldehyde of formula (II) with 6-fluoro-3- (4-piperidinyl)-1,2-benzisoxazole of formula (IV) or any of its salts to provide the intermediate enamine 3-{2-[4-(6-fluorobenzo [d] isoxazol-3-yl)-piperidin-1-yl]-vinyl}-2-methyl-6, 7,8, 9-tetrahydro-pyrido[1, 2-a] pyrimidin-4-one of formula (III) followed by reduction of same in the presence of a hydride, optionally in the presence of a salt, acid or inorganic base, and in the presence of a suitable inert solvent, the reactions being performed by either isolating intermediate (III) or not in a single-stage synthesis process. The compound of formula (I) is also known as risperidone, which is a pharmaceutically active compound for its antipsychotic properties. |