The general procedure for the synthesis of 1-Boc-4-(4-aminophenoxy)piperidine from tert-butyl 4-(4-nitrophenoxy)piperidine-1-carboxylate was as follows: 4-(1-tert-butoxycarbonylpiperidin-4-yloxy)nitrobenzene (11.9 g) obtained in Reference Example 105 was dissolved in methanol (100 mL) and palladium-carbon catalyst (1.9 g) was added. The reaction mixture was stirred at room temperature for 4 hours in a hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography with the eluent being a solvent mixture of hexane and ethyl acetate in the ratio of 1:1, v/v. The final product was 1-Boc-4-(4-aminophenoxy)piperidine (10.7 g, 99% yield) as a light red solid.1H NMR (400 MHz, CDCl3) δ ppm: 1.46 (9H, s), 1.71 (2H, m). 1.87 (2H, m), 3.27 (2H, m), 3.71 (2H, m), 4.26 (1H, m), 6.63 (2H, d, J = 8.5 Hz), 6.76 (2H, d, J = 8.5 Hz).
