[N:1]1([CH2:6][C:7]([CH:9]2[CH2:14][CH2:13][N:12]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:11][CH2:10]2)=[O:8])[CH2:5][CH2:4][CH2:3][CH2:2]1.[BH4-].[Na+].Cl>CO>[OH:8][CH:7]([CH:9]1[CH2:10][CH2:11][N:12]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:13][CH2:14]1)[CH2:6][N:1]1[CH2:5][CH2:4][CH2:3][CH2:2]1Tert-butyl 4-(2-pyrrolidin-1-ylacetyl)piperidinecarboxylate (0.33 g, 1.1 mmol) prepared according to Reference Example 12 was dissolved in methanol (5.0 mL), and was mixed with sodium borohydride (0.13 g, 3.3 mmol) added with stirring under ice-cooling, followed by stirring at room temperature for one hour. Diluted hydrochloric acid (1.0 mol/L, 0.5 mL) was added dropwise to the reaction mixture under ice-cooling, and the solvent was distilled off. The residue was diluted with water and was extracted with ethyl acetate. The organic layer was washed with brine, was dried over anhydrous sodium sulfate, and the solvent was distilled off. The residue was dried under reduced pressure and thereby yielded tert-butyl 4-(1-hydroxy-2-pyrrolidin-1-ylethyl)piperidinecarboxylate (0.24 g, 73%).
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