General procedure for the synthesis of 3-amino-4-phenylpyridine from 3-nitro-4-phenylpyridine: 3-nitro-4-phenylpyridine (600 mg, 3.00 mmol) and 10% palladium-carbon catalyst (319 mg, 0.150 mmol) were suspended in methanol (20 mL). The reaction mixture was stirred for 3 h at room temperature under hydrogen atmosphere (1 atm). Upon completion of the reaction, the catalyst was filtered through a diatomaceous earth pad to remove the catalyst. The filtrate was concentrated under reduced pressure to give an off-white solid 3-amino-4-phenylpyridine (420 mg, 2.468 mmol, 82% yield). The structure of the product was confirmed by NMR hydrogen spectroscopy (400 MHz, DMSO-d6): δ 8.11 (s, 1H), 7.85 (d, J = 4.8 Hz, 1H), 7.54-7.47 (m, 4H), 7.45-7.38 (m, 1H), 7.00 (d, J = 4.5 Hz, 1H), 5.10 (br.s., 2H); liquid chromatography-mass spectrometry (ESI) showed m/z 171.1 [(M + H)+, calculated value C11H11N2 171.1].
