[NH2:1][C:2]1[CH:3]=[C:4]([N:11]2[CH2:16][CH2:15][N:14]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[CH2:13][CH2:12]2)[CH:5]=[CH:6][C:7]=1[N+:8]([O-])=O.[H][H]>[Pd].CO>[NH2:1][C:2]1[CH:3]=[C:4]([N:11]2[CH2:16][CH2:15][N:14]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[CH2:13][CH2:12]2)[CH:5]=[CH:6][C:7]=1[NH2:8]A 500 ml Parr hydrogenation flask was charged with tert-butyl 4-(3-amino-4-nitrophenyl)piperazine-1-carboxylate (9.0 g), methanol (250 mL) and 10% palladium on carbon (50% w/w water, 2.0 g). The atmosphere of the vessel was replaced by hydrogen gas. The reaction was shaken under a hydrogen atmosphere at 40 psi at room temperature for 1 hour. The reaction mixture was filtered through a plug of Celite, which was washed with additional methanol. The filtrate was concentrated at reduced pressure and the residue was triturated with ether to give 7.0 g of tert-butyl 4-(3,4-diaminophenyl)piperazine-1-carboxylate (yield 85%). 1H-NMR (400 MHz, MeOH-d4): δ 6.65 (d, 1H), 6.47 (s, 1H), 6.30 (d, 1H), 3.52 (s, 4H) 2.90 (s, 4H), 1.48 (s, 9H). MS (EI) for: 293 (MH+).
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