Reaktion #82192

Reaktionsgleichung

methyl (2R,3S)-3-(tert-butoxycarbonylamino)-2-hydroxy-3-phenylpropionate

chloral

pyridinium p-toluenesulphonate

→

(4S,5R)-5-methoxycarbonyl-4-phenyl-2-trichloromethyl-1,3-oxazolidine

Ausbeute 91.0%

Lösungsmittel

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturat reflux with distillation of the solvent
2. 2
   workup.DISTILLATION15 cm3 of solvent are distilled
3. 3
   workup.ADDITION5 cm3 of chloral and 0.05 g of pyridinium p-toluenesulphonate are added
4. 4
   workup.DISTILLATION20 cm3 of solvent are distilled
5. 5
   workup.ADDITION5 cm3 of chloral as well as 30 cm3 of anhydrous toluene are added
6. 6
   workup.DISTILLATION25 cm3 of solvent are distilled
7. 7
   workup.ADDITION5 cm3 of chloral and 35 cm3 of anhydrous toluene are added
8. 8
   workup.DISTILLATION25 cm3 of solvent are distilled
9. 9
   WaschenThe organic solution is washed with water (2 times 50 cm3)
10. 10
    Trocknendried over sodium sulphate
11. 11
    Einengenconcentrated to dryness under reduced pressure at approximately 50° C
12. 12
    SonstigeThe residue obtained
13. 13
    Sonstigeis purified by liquid chromatography on silica gel

Vorschrift

A solution of 3.0 g of methyl (2R,3S)-3-(tert-butoxycarbonylamino)-2-hydroxy-3-phenylpropionate, of 5 cm3 of chloral and of 0.05 g of pyridinium p-toluenesulphonate in 40 cm3 of anhydrous toluene is heated at reflux with distillation of the solvent. 15 cm3 of solvent are distilled and then 5 cm3 of chloral and 0.05 g of pyridinium p-toluenesulphonate are added. 20 cm3 of solvent are distilled and then 5 cm3 of chloral as well as 30 cm3 of anhydrous toluene are added. 25 cm3 of solvent are distilled and 5 cm3 of chloral and 35 cm3 of anhydrous toluene are added. 25 cm3 of solvent are distilled and then the solution is cooled to a temperature in the region of 20° C. The organic solution is washed with water (2 times 50 cm3), dried over sodium sulphate and concentrated to dryness under reduced pressure at approximately 50° C. The residue obtained is purified by liquid chromatography on silica gel, the eluent being an ethyl acetate/cyclohexane (1/3 by volume) mixture. There are thus obtained, with a yield of 91%, 3.0 g of (4S,5R)-5-methoxycarbonyl-4-phenyl-2-trichloromethyl-1,3-oxazolidine whose characteristics are the following:

Quelle