[CH3:1][C@H:2]1[CH2:7][N:6]([CH2:8][C:9]2[CH:14]=[CH:13][C:12]([N+:15]([O-])=O)=[CH:11][CH:10]=2)[CH2:5][CH2:4][N:3]1[C:18]([O:20][C:21]([CH3:24])([CH3:23])[CH3:22])=[O:19].[OH-].[K+]>CO.[Pd]>[NH2:15][C:12]1[CH:13]=[CH:14][C:9]([CH2:8][N:6]2[CH2:5][CH2:4][N:3]([C:18]([O:20][C:21]([CH3:24])([CH3:23])[CH3:22])=[O:19])[C@@H:2]([CH3:1])[CH2:7]2)=[CH:10][CH:11]=1To 1,1-dimethylethyl (2S)-2-methyl-4-[(4-nitrophenyl)methyl]-1-piperazinecarboxylate (D1) (4.62 g, 13.78 mmol) and KOH (7.79 g, 138.8 mmol) in MeOH (100 mL) was added wet (50% w/w water) 10% Pd/C catalyst (4 g) and the mixture was hydrogenated at room temperature and atmospheric pressure for 40 mins. The catalyst was removed by filtration and the filtrate concentrated in vacuo. The residue was partitioned between DCM and water and aqueous layer was further extracted with DCM (×2). The combined organics were washed with brine, dried and concentrated to give the title compound as a colourless gum (4.14 g) which was used in the next step without further purification. δH (CDCl3, 400 MHz) 7.10 (2H, d), 6.64 (2H, d), 4.16 (1H, br.s), 3.78 (1H, d), 3.62 (2H, s), 3.42 (1H, d), 3.28 (1H, d), 3.08 (1H, td), 2.74 (1H, m), 2.58 (1H, m), 2.06 (1H, dd), 1.95 (1H, m), 1.46 (9H, s), 1.21 (3H, d).
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