[Synthesis]
General procedure for the synthesis of 2-bromo-4-(bromomethyl)pyridine from 2-bromo-4-pyridinemethanol: Phosphorus tribromide (13.4 mL, 143.62 mmol) was added slowly and dropwise to a solution of 2-bromo-4-pyridinemethanol (18 g, 95.74 mmol) in toluene (180 mL) under the protection of 0 °C and an inert atmosphere. The reaction mixture was warmed to 100 °C and maintained for 30 min. Upon completion of the reaction, the system was cooled to 0 °C and the reaction was quenched by the addition of saturated NaHCO3 solution, followed by extraction with ethyl acetate (2 x 500 mL). The organic phases were combined, dried with anhydrous Na2SO4 and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography using 15% ethyl acetate/hexane mixed solvent as eluent to afford the target product 2-bromo-4-(bromomethyl)pyridine (12.0 g, 50% yield). The product was characterized by 1H NMR (CDCl3, 400 MHz): δ 8.35 (d, J = 4.8 Hz, 1H), 7.51 (s, 1H), 7.26 (d, J = 6.0 Hz, 1H), 4.34 (s, 2H). Mass spectrometry (MS) analysis showed a molecular ion peak [M + H]+ of 251.80. |