2-(4-Nitrophenyl)butyric acid (10.0 g, 47.8 mmol) and carbon-loaded palladium catalyst (0.25 g) were suspended in methanol (100 mL). The reaction mixture was stirred overnight at room temperature and 1 atm hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by filtration through a diatomaceous earth pad and the diatomaceous earth was washed with methanol (50 mL). The filtrates were combined and concentrated using a rotary evaporator. Water (200 mL) was added to the concentrate and recrystallized. The mixture was cooled in an ice bath to precipitate a pink solid product. The solid was collected by vacuum filtration and dried under vacuum to give 5.8 g of 2-(4-aminophenyl)butyric acid in 68% yield. The product was characterized by the following data: NMR (400 MHz, DMSO-d6) δ 11.88 (s, 1H, COOH), 6.73 (d, J = 8.4 Hz, 2H, ArH), 6.31 (d, J = 8.4 Hz, 2H, ArH), 4.77 (s, 2H, NH2), 2.98 (t, J = 7.5 Hz, 1H, CH). 1.68 (m, 1H, CH2), 1.39 (m, 1H, CH2), 0.62 (t, J = 7.3 Hz, 3H, CH3); MS (ESI) m/z 202.1 ([M+Na]+).
