C([N:8]1[CH2:13][CH2:12][CH:11]([CH2:14][C:15]([N:17]2[CH2:22][CH2:21][CH:20]([OH:23])[CH2:19][CH2:18]2)=[O:16])[CH2:10][CH2:9]1)C1C=CC=CC=1.[H][H]>[C].[Pd].CC(O)C>[NH:8]1[CH2:9][CH2:10][CH:11]([CH2:14][C:15]([N:17]2[CH2:18][CH2:19][CH:20]([OH:23])[CH2:21][CH2:22]2)=[O:16])[CH2:12][CH2:13]114.2 g (0.05 mol) of 1-(1-benzyl-4-piperidylacetyl)-4-hydroxypiperidine [1] and 127.9 g of 2-propanol were mixed with each other. To this mixture, 1.42 g of 5% palladium-carbon (containing water at 50% content) was added. The reaction was allowed to proceed for 14 hours at 50° C. under the flow of hydrogen. The catalyst was removed by filtration therefrom, and the filtrate was concentrated under a reduced pressure. 23.6 g of acetonitrile was added to the concentrated residue, and the temperature of the mixture was increased to a reflux temperature of 80° C. The crystals which precipitated at room temperature were collected by filtration and the resultant wet crystals were dried under a reduced pressure, whereby 9.08 g of the title compound in the state of white powder was obtained (the yield was 89.4%).
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