Reaktion #9804

Reaktionsgleichung

H-Orn(Z)-OH

formic acid

acetic anhydride

→

For-Orn(Z)-OH

Ausbeute 88.0%

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe solution was cooled in an ice bath
2. 2
   Temperaturwas maintained between about 5° and 15° C
3. 3
   SonstigeThe resultant reaction mixture
4. 4
   workup.ADDITIONafter the addition
5. 5
   workup.WAITthe reaction vessel was refrigerated overnight
6. 6
   Einengenthe solution was concentrated to dryness under reduced pressure
7. 7
   Waschenwashed with water
8. 8
   Trocknenwith saturated NaCl, and then dried overnight over sodium sulfate
9. 9
   FiltrationAfter filtration and evaporation to dryness
10. 10
    workup.DISSOLUTIONthe residual syrup was dissolved in 5 L of ethyl ether
11. 11
    TemperaturThe solution was cooled in a dry ice bath
12. 12
    FiltrationThe resulting crystalline product was filtered
13. 13
    Waschenwashed with ethyl ether, air
14. 14
    Sonstigedried for two hours
15. 15
    Sonstigefinally dried in a lyophilizer

Vorschrift

444.7 g (1.67 mole) of commercially available H-Orn(Z)-OH was dissolved in 3.5 L (93 moles) of formic acid. The solution was cooled in an ice bath, and 1.17 L (12 moles) of acetic anhydride was subsequently added in dropwise fashion over two hours while the temperature of the reaction mixture was maintained between about 5° and 15° C. The resultant reaction mixture was stirred at room temperature for about two hours after the addition was completed, and the reaction vessel was refrigerated overnight. 1.5 L of cold water was then added, and the solution was concentrated to dryness under reduced pressure. The residual, light yellow syrup was taken up into EtOAc, washed with water and then with saturated NaCl, and then dried overnight over sodium sulfate. After filtration and evaporation to dryness, the residual syrup was dissolved in 5 L of ethyl ether. The solution was cooled in a dry ice bath and seeded. The resulting crystalline product was filtered, washed with ethyl ether, air dried for two hours and finally dried in a lyophilizer. 431.6 g (1.47 mole, 88%) of For-Orn(Z)-OH was obtained.

Quelle