Step 1: Tert-butyl 4-(2-methoxyphenyl)piperidine-1-carboxylate (2.6 g, 8.9 mmol) was dissolved in dichloromethane (35 mL) under nitrogen protection and cooled to -78 °C. Boron tribromide (2.45 g, 9.8 mmol) was added slowly. The reaction mixture was gradually warmed to room temperature and stirred overnight. Upon completion of the reaction, the reaction was quenched with ammonium hydroxide solution. The mixture was separated by extraction with dichloromethane (25 mL) and water (60 mL). The organic layer was dried with anhydrous sodium sulfate and concentrated under reduced pressure to give 2-(piperidin-4-yl)phenol (1 g, yield: 63%) as a white solid.1H NMR (400 MHz, DMSO-d6): δ=9.30 (brs, 1H), 7.09-7.04 (m, 1H), 6.99-6.95 (m, 1H), 6.80-6.72 (m, 2H), 3.72-3.69 (m, 1H), 3.08-3.06 (m, 1H), 2.95-2.93 (m, 1H), 2.85-2.83 (m, 1H), 2.68-2.63 (m, 1H), 1.72-1.50 (m, 4H).
