[Synthesis]
General procedure for the synthesis of 4-(4-bromophenyl)piperidin-4-ol hydrochloride from 4-(4-bromophenyl)-1,2,3,6-tetrahydropyridine hydrochloride: 4-(4-bromophenyl)piperidin-4-ol hydrochloride (600 mg, 2.34 mmol) was mixed with 6 M aqueous hydrochloric acid (15 mL) and heated to reflux for 5 hours. After completion of the reaction, the mixture was cooled to room temperature and allowed to stand overnight. The precipitated crystals were collected by filtration, washed sequentially with water and ether, and dried under vacuum to afford the target product 4-(4-bromophenyl)-1,2,3,6-tetrahydropyridine hydrochloride (434 mg, 68% yield) as a white solid with a melting point of 249-251°C. The product was then dried under vacuum. NMR hydrogen spectrum (CD3OD) δH: 7.54 (d, J=8.5 Hz, 2H, H3', H5'), 7.8 (d, J=8.5 Hz, 2H, H2', H6'), 6.20 (br s, 1H, H5), 3.88-3.83 (m, 2H, H6), 3.48 (dd, J=6 Hz, 2H, H2), 2.85- 2.76 (m, 2H, H3). NMR carbon spectrum (CD3OD) δC: 139.5 (Cq), 136.0 (Cq), 132.8 (CH), 128.0 (CH), 123.0 (Cq), 117.9 (CH), 43.4 (CH2), 42.1 (CH2), 24.7 (CH2). High performance liquid chromatography (HPLC) analysis showed a purity of 99.3% with a retention time (tR) of 6.50 min (isocratic conditions, 40% B); 99.2% with a tR of 9.66 min (gradient conditions). High resolution mass spectrometry (HRMS) calculated value C11H13BrN+ [M+H]+: 238.0226, measured value: 238.0235. |