C([O-])(=O)C.[NH4+].[CH2:6]([N:13]1[CH2:18][CH2:17][C:16](=O)[C:15]([CH2:22][CH3:23])([CH2:20][CH3:21])[CH2:14]1)[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.C([BH3-])#[N:25].[Na+]>CO>[NH2:25][CH:16]1[CH2:17][CH2:18][N:13]([CH2:6][C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)[CH2:14][C:15]1([CH2:22][CH3:23])[CH2:20][CH3:21]Ammonium acetate (7.85 g, 102 mmol) was added to the stirred solution of 1-benzyl-3,3-diethyl piperidin-4-one (5.0 g, 20.40 mmol) in methanol (100 ml) and stirring was continued for 3 hr at ambient temperature. The resulting mixture was cooled at 0° C. and sodium cyanoborohydride (1.3 g, 20.40 mmol) was added to it. Cooling was removed after 10 min. and resulting mixture was stirred for 6 hr at ambient temperature. The reaction mixture was concentrated to dryness, triturated with water, acidified with conc. HCl (pH 3˜4) and extracted with ethyl acetate to remove impurities. The aqueous layer was basified with 1 M sodium hydroxide solution (pH˜10) and extracted with ethyl acetate. Ethyl acetate extract was dried (Na2SO4) and concentrated to dryness to furnish 4-amino-1-benzyl-3,3-diethyl piperidine. Yield 8.2 g (82%), C16H26N2, m/z 247 (M+1), PMR (CDCl3): 0.84 (s, 3H), 0.98 (s, 3H), 1.48 (bs, 2H, D2O exchangeable), 1.66 (m, 2H), 2.04 (m, 2H), 2.42 (m, 2H), 2.86 (m, 1H), 3.46 (dd, 2H), 7.32 (m, 5H).
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