[C:1]([O:5][C:6]([N:8]1[CH2:15][CH:14]2[C:16](=O)[CH:10]([CH2:11][CH:12]([C:18]([O:20][CH3:21])=[O:19])[CH2:13]2)[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].S(NN)(C1C=CC(C)=CC=1)(=O)=O.C([BH3-])#N.[Na+]>C1COCC1>[C:1]([O:5][C:6]([N:8]1[CH2:9][CH:10]2[CH2:16][CH:14]([CH2:13][CH:12]([C:18]([O:20][CH3:21])=[O:19])[CH2:11]2)[CH2:15]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]To a solution of methyl 3-(tert-butoxycarbonyl)-9-oxo-3-azabicyclo[3.3.1]nonane-7-carboxylate (14.76 g, 49.63 mmol), in anhydrous THF (250 mL) was added tosylhydrazine (11.1 g, 59.6 mmol), and the mixture was stirred for 2 h at ambient temperature. The reaction mixture was heated to 65° C., sodium cyanoborohydride (12.5 g, 198 mmol) was added, and the mixture was stirred for 16 h at 65° C. The reaction mixture was cooled to ambient temperature and concentrated by rotary evaporation. The residue was purified by flash silica gel chromatography, using an ethyl acetate in hexane gradient, to give 8.71 g (61.9% yield) of the methyl 3-(tert-butoxycarbonyl)-3-azabicyclo[3.3.1]nonane-7-carboxylate as a colorless solid (1H NMR (CDCl3): δ 3.97-3.8 (m, 2H), 3.65 (s, 3H), 2.85-2.75 (m, 2H), 2.57-2.47 (m, 1H), 2.38-2.20 (m, 2H), 2.0-1.7 (m, 4H), 1.68-1.60 (m, 1H), 1.52-1.41 (m, 1H), 1.41 (s, 9H); LC-MS (MH+): 284).
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