1033610-45-5

18677-48-0

1033610-45-5

The general procedure for the synthesis of 4-bromo-3,5-dimethoxypyridine from 3,5-dimethoxypyridine was as follows: n-butyllithium (23.3 mmol, 2M cyclohexane solution) was slowly added to a stirred anhydrous THF solution of 3,5-dimethoxypyridine (2.7 g, 19.4 mmol) at -78 °C. During the addition, a precipitate was formed in the reaction mixture, after which the reaction system was slowly warmed to room temperature and held for 5 minutes. After separation of the precipitate, the reaction mixture was again cooled to -78 °C and bromine (1.5 ml, 29.1 mmol) was added dropwise, followed by another warming to room temperature. After stirring for 10 min, the reaction mixture became homogeneous and the reaction was quenched with 10% Na2S2O3 aqueous solution and subsequently extracted with EtOAc. The organic layer was washed with brine, dried over anhydrous MgSO4, concentrated under reduced pressure and the residue was adsorbed onto silica gel. Purification by fast column chromatography (silica gel, elution gradient: hexane/EtOAc, 2:1→1:1→1:2) afforded 4-bromo-3,5-dimethoxypyridine as a white solid (2.4 g, 57% yield).1H-NMR (300 MHz, CDCl3) δ 7.95 (s, 2H), 3.99 (s, 6H).