1'-(Benzyloxycarbonyl)spiro[3H-indole-3,4'-piperidin]-2(1H)-one (74.6 mg) was used as a raw material and dissolved in methanol (1.5 mL). 10% palladium/carbon catalyst (14 mg) was added and the reaction was stirred at room temperature under hydrogen atmosphere for 4 hours. Upon completion of the reaction, the insoluble material was removed by filtration. To the filtrate, 1N aqueous hydrochloric acid (0.33 mL) was added, followed by evaporation of the solvent under reduced pressure to afford spiro[indoline-3,4-piperidin]-2-one hydrochloride (51.7 mg) in 98% yield. The product was characterized by 1H-NMR (D2O): δ 2.11 (4H, m), 3.48 (2H, m), 3.72 (2H, m), 7.07 (1H, d, J = 8 Hz), 7.18 (1H, t, J = 8 Hz), 7.35 (1H, t, J = 8 Hz), 7.45 (1H, d, J = 8 Hz). Mass spectrometry (TSP) analysis showed: m/z 203 (MH+).