Patent ID: 7205405

Claim:
A process for the preparation of 3-{2-[4-(6-fluoro-benzo[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: which 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 in a single stage synthesis without isolating intermediate III.