Synthese
General procedure for the synthesis of 5-aminomethyl-2-bromopyridine from 2-bromo-5-(bromomethyl)pyridine: 2-bromo-5-methylpyridine (70.0 mmol) and N-bromosuccinimide (80.0 mmol) were dissolved in 1,2-dichloroethane (150 mL), followed by addition of 2,2'-azino-bis(2-methylpropionitrile) (1.50 mmol). The reaction mixture was heated at reflux for 15 minutes at 85 °C, another portion of 2,2'-azobis(2-methylpropionitrile) (1.50 mmol) was added and heating was continued at 85 °C for 15 minutes. After completion of the reaction, it was cooled to room temperature and the reaction mixture was allowed to stand at 5 °C for 2 h. The precipitate was collected by filtration and washed with a small amount of 1,2-dichloroethane. The filtrate was concentrated under reduced pressure and the resulting crude product was used directly in the next step of the reaction. The crude 2-bromo-5-(bromomethyl)pyridine was dissolved in chloroform (100 mL) and urotropine (70.0 mmol) was added. The reaction mixture was stirred at room temperature for 16 h. The precipitate was collected by filtration, washed with a little chloroform and dried in air. The resulting urotropin salt was mixed with concentrated hydrochloric acid and refluxed for 90 minutes, cooled to room temperature and then a mixture of 40% aqueous formaldehyde (5.0 mL) and ammonium hydroxide (12 mL) and water (80 mL) was added under stirring. The precipitate was collected by filtration, washed with ice water and dried in a vacuum desiccator. The crude product was purified by recrystallization from ethanol. Yield: 40%, melting point: 105-106 °C. Elemental analysis: calculated value of C5H7BrN2 (187.04): C, 38.53; H, 3.77; N, 14.98. measured value: C, 38.22; H, 3.72; N, 14.71. hplc-MS (ESI+): m/z 188.02 (97.2%). 1H NMR (DMSO-d6): δ 4.04 (t. J=5.67 Hz, 2H, CH2), 7.71 (d, J=8.19 Hz, 1H, ArH), 7.95 (dd, J=8.19, J'=1.95 Hz, 1H, ArH), 8.51 (d, J=1.95 Hz, 1H, ArH), 8.74 (s, br, 2H, NH2).
