Methyl 3-(piperidin-4-yl)propanoate (WO2004/92124 A2) (206 mg, 1.11 mmol) was dissolved in N,N-dimethylformamide (10 mL), tert-butyl 4-fluorobenzoate (141 mg, 1.11 mmol) and potassium carbonate (100 mg, 1.11 mmol) were added, and the mixture was stirred at 120° C. under a nitrogen atmosphere for 16 hours. After the reaction was completed, a saturated aqueous sodium hydrogencarbonate solution was added to the reaction mixture under ice cooling, and ethyl acetate was further added to separate the layers. The resulting organic layer was separated, washed with saturated sodium chloride solution, and then dried with anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by NH silica gel column chromatography (hexane:ethyl acetate, 10:1, v/v) to give the title compound (126 mg; yield, 31%) as a colorless oily substance.
