反应详情

Heat a mixture of (S)-2-(2-oxoethyl)-piperazine-1,4-dicarboxylic acid di-tert-butyl ester (1.38 g, 4.21 mmol) and (carbethoxymethylene)triphenylphosphorane (1.87 g, 5.38 mmol) in THF (17 mL) at reflux for 4 h. Concentrate the mixture under reduced pressure and purify by silica gel chromatography eluting with 20% to 50% EtOAc in hexanes. Combine the purified fractions, concentrate under reduced pressure, azeotrope with CH2Cl2/hexanes (1:2) and place under vacuum to give the title compound: yellow tar (0.961 g), mass spectrum (m/e): 416.09(M+NH4).

1. temperatureHeat
2. temperatureat reflux for 4 h
3. concentrationConcentrate the mixture under reduced pressure
4. custompurify by silica gel chromatography
5. washeluting with 20% to 50% EtOAc in hexanes
6. concentrationCombine the purified fractions, concentrate under reduced pressure, azeotrope with CH2Cl2/hexanes (1:2) and place under vacuum