Ethyl 4-(1-benzyloxycarbonyl-4-piperidyl)-2-chlorobutyrate → 4-Piperidinebutanoic acid, ethyl ester

In 20 ml of ethanol is dissolved 10.5 g of ethyl 4-(1-benzyloxycarbonyl -4-piperidyl)-2-chlorobutyrate, and a catalytic reduction reaction is carried out at ordinary temperature and at atmosphereic pressure using 5 g of 10% palladium-carbon (50% in water ) as a catalyst. After absorption of hydrogen stops, the catalyst is removed by filtration, and the filtrate is concentrated under reduced pressure to give ethyl 4-(4-piperidyl)butyrate. This product is dissolved in a mixture of 200 ml of ethyl acetate and 100 ml of water, 6 g of sodium hydrogencarbonate is added to the solution, followed by stirring at room temperature. Benzyloxycarbonyl chloride (6 ml) is added dropwise to the mixture, and after the addition is completed, the mixture is stirred at room temperature for 1.5 hours. The ethyl acetate layer is separated, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue is purified by silica-gel column chromatography (hexane:ethyl acetate=3:1) to give 5.3 g of ethyl 4-(1-benzyloxycarbonyl-4 -piperidyl)butyrate as a colorless oily material.