反应详情

A solution of 2.07 g of ethyl (2R,3S)-3-cyclopropyl-3-tert -butoxycarbonylamino-2-hydroxypropionate and 213 mg of pyridinium p-toluenesulfonate in 125 ml of toluene is refluxed under heating. To the mixture is added dropwise a solution of 2.76 g of p-anisaldehydedimethylacetal in 25 ml of toluene for 20 minutes. The reaction mixture is evaporated to remove the generated methanol. The mixture is stirred under heating for 1.5 hours and cooled. After the reaction mixture is condensed under reduced pressure, ethyl acetate and water are added to the residue. The ethyl acetate layer is obtained by separation. The aqueous layer is extracted with ethyl acetate. The extract is washed with water and brine, dried and condensed under reduced pressure. The residue is purified by silica gel column chromatography (solvent; toluene:ethyl acetate=40:1) to give 1.572 g of ethyl (4S,5R)-3-tert-butoxycarbonyl-2-(4-methoxyphenyl)-4-cyclopropyl-5-oxazolidinecarboxylate (diastereomeric mixture).

1. temperatureunder heating
2. customThe reaction mixture is evaporated
3. customto remove the generated methanol
4. temperatureunder heating for 1.5 hours
5. temperaturecooled
6. customcondensed under reduced pressure, ethyl acetate and water
7. additionare added to the residue
8. extractionThe aqueous layer is extracted with ethyl acetate
9. washThe extract is washed with water and brine
10. customdried
11. customcondensed under reduced pressure
12. customThe residue is purified by silica gel column chromatography (solvent; toluene:ethyl acetate=40:1)