A solution of 5-fluoro-N-(2-methyl-1-phenylpropyl)-2-nitrobenzenamine (1.79 g, 6.2 mmol), N-Boc-piperazine (1.16 g, 6.2 mmol) and N,N-diisopropylethylamine (2.2 mL, 12.4 mmol) in acetonitrile was stirred at reflux for 24 h. The reaction mixture was cooled down and concentrated under reduced pressure. The residue was taken up in dichloromethane, washed with water, dried and concentrated in vacuo to yield 2.45 g of the crude aniline. The crude product was purified by PTLC (15% ethyl acetate in hexanes) to yield 1.75 g (62%) of tert-butyl 4-(3-(2-methyl-1-phenylpropylamino)-4-nitrophenyl)piperazine-1-carboxylate: 1H NMR (400 MHz, CD3OD): δ 9.01 (br d, 1H), 7.96 (dd, 1H), 7.33-7.32 (m, 4H), 7.25-7.24 (m, 1H), 6.27 (br d, 1H), 5.72 (s, 1H), 4.40 (t, 1H), 3.42-3.34 (m, 4H), 3.27-3.23 (m, 2H), 3.16-3.11 (m, 2H), 2.13 (m, 1H), 1.07 (d, 3H), 0.96 (d, 3H). MS (ESI) m/z: Calculated: 454.26; Observed: 477.3 (M++Na).
