Ethyl 2-hydroxyisobutyrate → Ethyl 2-fluoroisobutyrate
Reaktionsgleichung
O[C:2]([CH3:9])([CH3:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].C(N(S(F)(F)[F:16])CC)C>C(Cl)Cl>[F:16][C:2]([CH3:9])([CH3:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Reaktionsbedingungen
- Temperatur
- -70 °C
Versuchsvorschrift
Ethyl 2-hydroxyisobutyrate (12.43 g) was stirred in dry methylene chloride (65 ml) at -70° C. under nitrogen. Diethylaminosulphur trifluoride (30.32 g) in dry methylene chloride (5 ml) was added slowly, maintaining the temperature at -70° C. After completion of the addition, the mixture was stirred at -70° C. for 1 hour and was then allowed to warm to room temperature, stood for 3 hours and then overnight. The reaction was then carefully added to ice with vigorous stirring, and the resultant methylene chloride layer combined with a further methylene chloride extract of the aqueous layer. The total organic fraction was washed with brine, dried over magnesium sulphate and the solvent carefully distilled, to leave ethyl 2-fluoro-isobutyrate as a bronze liquid (12.8 g); 1H NMR analysis indicated that this material was >95% pure, and contained 2-3% of ethyl methacrylate. NMR (CDCl3, 270 MHz) δ 1.31(3H,t), 1.58(6H,d), 4.25(2H,q) ppm; 1H NMR (CDCl3, 254 MHz, 19F) δ -148.0 (1F, septet) ppm.