1.44 g of 4-tert-butoxycarbonylaminopiperidine was dissolved in 14 ml of N,N-dimethylformamide. Thereafter, 1.99 g of potassium carbonate and 1.87 g of 4-(3-bromopropoxy)benzonitrile were successively added to the above solution, followed by stirring at room temperature for 24 hours. Water and ethyl acetate were added to the reaction mixture, so that the organic layer was separated. The separated organic layer was washed with a saturated aqueous solution of sodium chloride, and then dried over anhydrous magnesium sulfate. Thereafter, the solvent was removed under a reduced pressure. The obtained solid was filtrated with a mixed solution consising of n-hexane and diisopropyl ether to obtain 2.12 g of tert-butyl 1-[3-(4-cyanophenoxy)propyl]-4-piperidinylcarbamate.
