反应详情

To a mechanically-stirred solution of ethyl acetoacetate (59 mL, 463 mmol) in ether (75 mL) was added bromine (23.5 mL, 912 mmol) while the reaction temperature was maintained below 23° C. using an ice-water bath. The yellow-orange solution was stirred for 5 hours with cooling and then was stirred overnight at ambient temperature. Ice (60 g) was added and the reaction mixture was extracted with ether. The organic phase was washed twice with aqueous NaHCO3 saturated with NaCl and once with brine. The ether solution was stirred for 1 day over CaCl2 and then was filtered through celite. The filter cake was rinsed with dichloromethane. The filtrate was concentrated in vacuo to give ethyl 4-bromoacetoacetate (71.5 g) which was stored in the dark and stabilized with BaCO3 (300 mg).

1. temperaturewas maintained below 23° C.
2. temperaturewith cooling
3. stirringwas stirred overnight at ambient temperature
4. extractionthe reaction mixture was extracted with ether
5. washThe organic phase was washed twice with aqueous NaHCO3 saturated with NaCl and once with brine
6. stirringThe ether solution was stirred for 1 day over CaCl2
7. filtrationwas filtered through celite
8. washThe filter cake was rinsed with dichloromethane
9. concentrationThe filtrate was concentrated in vacuo