[CH2:1]([O:3][C:4]([N:6]1[CH2:11][CH2:10][CH:9]([NH:12][C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][C:14]=2[N+:19]([O-])=O)[CH2:8][CH2:7]1)=[O:5])[CH3:2]>CO.[Pd]>[CH2:1]([O:3][C:4]([N:6]1[CH2:11][CH2:10][CH:9]([NH:12][C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][C:14]=2[NH2:19])[CH2:8][CH2:7]1)=[O:5])[CH3:2]4-(2-Nitro-phenylamino)-piperidine-1-carboxylic acid ethyl ester (from step 1 above) was dissolved in methanol then hydrogenated over 10% Pd/C (balloon pressure). The hydrogenation was run until the yellow color turned colorless. It was filtered through a celite pad, and the filtrated evaporated to a reddish brown residue. The residue was triturated with 1% ethyl acetate in hexanes and the solid collected by filtration to give 4-(2-amino-phenylamino)-piperidine-1-carboxylic acid ethyl ester (2.02 g; 77%, 2 steps). 1H NMR (CDCl3) δ 1.27 (t, 3H, J=7.2), 1.4 (m, 2H), 2.05 (m, 2H), 3.0 (m, 2H), 3.4 (m, 4H), 4.1 (m, 4H), 6.7 (m, 4H)
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