To grinded aluminum chloride (26 g) are added chlorobenzene (26 ml) and N-(α-methylcinnamoyl)-N-(1-benzyl-4-piperidinyl)aniline (8.7 g) and the mixture is heated at 110° C. for 1 hour. After cooling, the reaction mixture is poured into ice-water and made alkaline with an aqueous sodium hydroxide solution. After extraction with dichloromethane, the extract is concentrated and the resulting residue is purified by silica gel column chromatography (eluent; methylene chloride). The purified substance is converted into hydrochloride and then recrystallized from ethanol/water to give 1-(1-benzyl-4-piperidinyl)-3-methylcarbostyril hydrochloride (5.8 g) as colorless needles, m.p. 274°-276° C.
