A PROCESS FOR THE PREPARATION OF ANTI-PSCHOTIC 3-[2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]ethyl]-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2,-a]pyrimidin-4-one

摘要

A process for the preparation of 3-substituted ethyl-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2,-a]pyrimidin-4-one of formula (IIB) where X may be halo, acyloxy, or sulfonyloxy such as tosyloxy or mesyloxy, an intermediate in the synthesis of the anti-psychotic risperidone. The process comprises hydrogenation of 3-substituted ethyl-2-methyl-4H-pyrido[1,2,-a]pyrimidin-4-one in aqueous inorganic acid medium at atmospheric to 60 psi at 0-100 DEG C in the presence of a metal catalyst and the product is isolated. A process for the preparation of risperidone of formula (I) comprising condensation of 3-substituted ethyl-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2,-a]pyrimidin-4-one with 6 fluoro-3-(4-piperidinyl)-1, 2-benzosoxazolein water in the presence of an inorganic base at 25 - 100 DEG C and the product is isolated.