Reaktion #55201

Reaktionsgleichung

potassium hydroxide

triphenylphosphoranylideneacetic acid ethyl ester

4-(1-bromoethyl)-2',4'-difluorobiphenyl

ethyl acetate

→

3-(2',4'-difluoro-4-biphenylyl)butyric acid

Lösungsmittel

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturunder reflux for 54 hours
2. 2
   FiltrationThe precipitate is filtered off
3. 3
   Sonstigethe filtrate is evaporated
4. 4
   SonstigeCrude [1-(2',4'-difluoro-4-biphenylyl)ethyl]-triphenylphosphoranylideneacetic acid ethyl ester thus obtained
5. 5
   workup.DISSOLUTIONis dissolved in 500 ml
6. 6
   Temperaturthe mixture is heated
7. 7
   Temperaturunder reflux for one hour
8. 8
   workup.DISTILLATIONThe methanol is distilled off
9. 9
   workup.ADDITIONwater is added
10. 10
    Waschenthe reaction mixture is washed with ether

Vorschrift

69.7 g. of triphenylphosphoranylideneacetic acid ethyl ester and 29.7 g. of 4-(1-bromoethyl)-2',4'-difluorobiphenyl in 300 ml. of absolute ethyl acetate are heated under reflux for 54 hours. The precipitate is filtered off and the filtrate is evaporated. Crude [1-(2',4'-difluoro-4-biphenylyl)ethyl]-triphenylphosphoranylideneacetic acid ethyl ester thus obtained is dissolved in 500 ml. of methanol to which 150 ml. of 20% potassium hydroxide solution are added and the mixture is heated under reflux for one hour. The methanol is distilled off, water is added and the reaction mixture is washed with ether and acidified with hydrochloric acid to give 3-(2',4'-difluoro-4-biphenylyl)butyric acid, m.p. 109°-110°.

Quelle