Hydrochloric Acid → 2-Bromo-5-methoxypyrazine

温度

-10 °C

Methanolic hydrogen chloride (0.8 mL of a 10M methanolic solution) was added to a stirred solution of 2-amino-5-bromopyrazine (6.96 g, 0.04 mol) in anhydrous methanol (125 mL). To this cooled (-10° C.) solution was added isoamyl nitrite (16.1 mL, 0.12 mol) and the reaction mixture was stirred at -10° C. for 1.5 hours then at room temperature for 2 hours. The solvent was evaporated and the residue partitioned between aqueous saturated sodium carbonate (50 mL) and dichloromethane (4×50 mL). The combined organics were dried (sodium carbonate) and evaporated to give a brown oil which was purified by column chromatography on silica using 5% ethyl acetate in petroleum ether (60-80) to afford 2-bromo-5-methoxypyrazine as a pale yellow solid (6.45 g, 85%).