Risperidone has been reported to have neuroleptic activity. In this study, risperidone was synthesized using a new method involving a stille reaction, in which 2-methyl-3-vinyl-6,7,8,9-tet­rahydropyrido[1 ,2-a]pyrimidin-4-one was synthesized (5). The chemical synthesis process was found to be simple and produced risperidone in a high yield. In addition, can be easily scaled up for large scale synthesis.