Under nitrogen protection, 5-nitro-2-phenyl-1H-indole (2.83 g, 10 mmol) was dissolved in methanol (30 mL) and Raney Ni catalyst (510 mg) was added. The reaction mixture was placed under hydrogen atmosphere (1 atm) and the reaction was stirred at room temperature overnight. Upon completion of the reaction, the catalyst was removed by filtration through a diatomaceous earth pad and the filtrate was concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate=5:1) to afford 2-phenyl-1H-indol-5-amine (1.6 g, 77% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3) and mass spectrometry (ESI): 1H NMR δ 7.76 (d, J=7.6 Hz, 2H), 7.39 (t, J=7.6 Hz, 2H), 7.24 (t, J=7.6 Hz, 1H), 7.07 (d, J=8.4 Hz, 1H), 6.64 (d, J=1.6 Hz, 1H), 6.60 (d, J=1.2 Hz, 1H), 6.48 (dd, J=2.0,8.4 Hz, 1H), 4.48 (brs, 2H); MS (ESI) m/e 209.0 ([M+H]+).
