反应详情

3-bromo-5-chloropyridine (25 g, 130 mmol) in THF (50 mL) was added slowly to a solution of LDA (140 mmol) in THF (250 mL) at −78° C. over 10 minutes. After stirring for 30 minutes, ethyl chloroformate (26 mL, 260 mmol) in THF (30 mL) was added in portions over 5 minutes. After 10 more minutes, the reaction mixture was poured into cold 10% aqueous NaHCO3 (500 mL). The mixture was extracted with ethyl acetate (2×250 mL). The organic layer was dried over MgSO4 and evaporated. The crude solid was filtered through a silica pad with hexane (500 mL). The filtrate was evaporated to provide pure ethyl 3-bromo-5-chloropyridine-4-carboxylate (28 g, 80% yield).

1. extractionThe mixture was extracted with ethyl acetate (2×250 mL)
2. dry with materialThe organic layer was dried over MgSO4
3. customevaporated
4. filtrationThe crude solid was filtered through a silica pad with hexane (500 mL)
5. customThe filtrate was evaporated