The general procedure for the synthesis of 1-(4-aminophenyl)-4-hydroxypiperidine from 1-(4-nitrophenyl)piperidin-4-ol was as follows: 1-(4-nitrophenyl)piperidin-4-ol (1.50 g, 6.75 mmol) was dissolved in methanol (25 ml) and 10% palladium-carbon catalyst (150 mg) was added. The reaction system was replaced with hydrogen atmosphere and the reaction was stirred at room temperature for 2 hours. After completion of the reaction, the reaction mixture was filtered through diatomaceous earth and the filter cake was washed with methanol. The filtrate and washings were combined and the solvent was removed by distillation under reduced pressure to afford the target product 1-(4-aminophenyl)-4-hydroxypiperidine (1.28 g, 99% yield). The structure of the product was confirmed by 1H-NMR (CDCl3/TMS) with the following chemical shifts δ ppm: 1.70-1.80 (m, 2H), 2.07 (br, 2H), 2.84 (br, 2H), 3.37 (br, 3H), 3.85 (br, 1H), 6.65 (d, J=8.4 Hz, 2H), 6.91 (br, 2H) .
