[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH2:9][CH2:10][N:11]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[CH2:12][CH:13]=2)=[CH:4][C:3]=1[N+:21]([O-])=O.[H][H]>C(OCC)(=O)C.CO.[Pd]>[C:17]([O:16][C:14]([N:11]1[CH2:10][CH2:9][CH:8]([C:5]2[CH:6]=[CH:7][C:2]([F:1])=[C:3]([NH2:21])[CH:4]=2)[CH2:13][CH2:12]1)=[O:15])([CH3:20])([CH3:18])[CH3:19]A mixture of tert-butyl 4-(4-fluoro-3-nitrophenyl)-3,6-dihydro-1(2H)-pyridinecarboxylate (2.35 g, 8.85 mmol) and 10% Pd/C (400 mg) in ethyl acetate (40.0 mL) and methanol (10.0 mL) was hydrogenated at room temperature for 72 hours using hydrogen bomb (200 psi). The reaction mixture was filtered through Celite and the Celite was washed with EtOAc/MeOH (1:1, 3×50 mL). The filtrate was concentrated in vacuo to afford tert-butyl-4-(3-amino-4-fluorophenyl)-1-piperidinecarboxylate (2.10 g, 98.0%): 1H NMR (400 MHz, CDCl3) δ 6.96-6.76 (m, 1H), 6.67-6.54 (m, 1H), 6.54-6.40 (m, 1H), 4.38-4.09 (br, 2H), 4.09-3.58 (br, 2H), 2.87-2.62 (m, 2H), 2.60-2.39 (m, 1H), 1.85-1.65 (m, 2H), 1.64-1.40 (m, 2H), 1.48 (s, 9H).
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