Synthesis
GENERAL STEPS: 1.8 g (27 mmol) of methylamine hydrochloride and 0.4 g (6 mmol) of sodium cyanoborohydride were added sequentially to a 20 mL methanol solution containing 1 g (5.4 mmol) of 5-bromopyridine-3-carbaldehyde. The reaction mixture was stirred at room temperature for 48 hours. After completion of the reaction, the precipitate was removed by filtration and the filtrate was concentrated to dryness under reduced pressure. The residue was dissolved in dichloromethane and washed with deionized water. After separating the organic phase, the organic phase was washed with dilute aqueous hydrochloric acid. The acid-washed aqueous phase was adjusted to pH 9 with aqueous sodium hydroxide and subsequently extracted with dichloromethane. The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with dichloromethane/methanol (9.5:0.5, v/v) as eluent. 0.5 g (50% yield) of N-methyl-(5-bromopyridin-3-yl)methylamine was finally obtained.
