[CH3:1][C:2]([CH3:14])([O:4][C:5]([N:7]1[CH2:12][CH2:11][C:10](=O)[CH2:9][CH2:8]1)=[O:6])[CH3:3].[CH2:15]([NH2:19])[CH2:16][CH2:17][CH3:18].C([BH3-])#N.[Na+].Cl>CO.C(O)(=O)C>[CH3:1][C:2]([CH3:14])([O:4][C:5]([N:7]1[CH2:12][CH2:11][CH:10]([NH:19][CH2:15][CH2:16][CH2:17][CH3:18])[CH2:9][CH2:8]1)=[O:6])[CH3:3]
A mixture of 1-(1,1-dimethylethoxycarbonyl)-4-piperidone (IX, 1.50 g) in methanol (15 ml) under nitrogen is cooled in an ice bath, treated with butylamine (X, 0.93 ml) and sodium cyanoborohydride (235 mg), adjusted to pH 5 with glacial acetic acid as determined on moistened pH test paper, and stirred at 20°-25° for 24 hrs during which additional sodium cyanoborohydride (115 mg) is added. The mixture is then adjusted to pH 3 using hydrochloric acid (3M) and concentrated under reduced pressure, the residue is diluted with water (20 ml) and extracted with ether (2×20 ml), and the organic phase is discarded. The aqueous phase is adjusted to pH 12 with potassium hydroxide, saturated with sodium chloride, and extracted with methylene chloride (3×25 ml). The combined organic phase is dried over sodium sulfate and concentrated under reduced pressure to give the title compound, Anal. Calcd for C14H28N2O2 : C=65.59, H=11.01, N=10.93, found: C=65.44, H=11.05, N=10.81.
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