METHOD FOR PREPARING 3-{2-[4-(6-FLUOROBENZO[D]ISOXAZOLE-3-YL)PIPERIDINE-1-YL]ETHYL}-2-METHYL-6,7,8,9-TETRAHYDRO-4H-PYRIDO[1,2-A]PYRIMIDINE-4-ONE, INTERMEDIATE DERIVATIVES FOR ITS PREPARING AND METHOD FOR PREPARING INTERMEDIATE DERIVATIVE Russian patent published in 2006 - IPC C07D471/04 

FIELD: organic chemistry, chemical technology, pharmacy.

SUBSTANCE: invention relates to a method for preparing a pharmaceutically active compound 3-{2-[4-(6-fluorobenzo[d]isoxazole-3-yl)piperidine-1-yl]ethyl}-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-4-one (risperidone) of the formula (I): that possesses the neuroleptic properties. Method involves the condensation reaction of (2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-3-yl)acetaldehyde of the formula (II): with (6-fluoro-3-piperidinyl)-1,2-benzisoxazole of the formula (IV): to yield intermediate enamine representing 3-{2-[4-(6-fluorobenzo[d]isoxazole-3-yl)piperidine-1-yl]vinyl}-2-methyl-6,7,8,9-tetrahydropyrido[1,2-a]pyrimidine-4-one of the formula (III): and the following reduction of this enamine in the presence of hydride. Also, invention claims intermediate compounds of the formula (II) and formula (III) and describes a method for preparing compound of the formula (II) comprising oxidation of 3-(2-hydroxyethyl)-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-4-one of the formula (X): Method is characterized by high reproducibility in large-scale manufacturing and represents the unique combination of the synthesis simplicity, decreased cost, safety and protection of the environment.

EFFECT: improved preparing method.

9 cl, 3 ex