O=[C:2]1[CH2:19][CH2:18][C:5]2([CH2:10][CH2:9][N:8]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:7][CH2:6]2)[CH2:4][CH2:3]1.[NH3:20].CO.[BH4-].[Na+]>CCO>[NH2:20][CH:2]1[CH2:19][CH2:18][C:5]2([CH2:10][CH2:9][N:8]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:7][CH2:6]2)[CH2:4][CH2:3]1To a solution of tert-butyl 9-oxo-3-azaspiro[5.5]undecane-3-carboxylate (5.35 g, 20.0 mmol) in EtOH (40 mL) were added a solution of NH3 in MeOH (7M, 40 mL, 280.0 mmol) and Ti(Oi-Pr)4 (11.30 g, 40.0 mmol), the mixture was stirred at room temperature overnight. And then NaBH4 (1.51 g, 40.0 mmol) was added portionwise. After addition, the resulting mixture was stirred at room temperature for another 5 h, then quenched with water (40 mL), stirred for 1 h and filtered. The filtrate was concentrated in vacuo, and the residue was purified by silica gel column chromatography (MeOH/DCM (v/v)=1/25) to give the product as a light yellow solid (1.20 g, 22.4%).
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