反应详情

温度

-78 °C

To a solution (S)-(−)-4-benzyl-2-oxazolidinone (7.8 g, 43.8 mmol) in THF (300 mL) at −78° C. was slowly added 1.6M n-butyllithium (27.3 mL, 43.8 mmol). The mixture was stirred for 30 minutes at −78° C. and a mixture of the compound of Step 1 (10.5 g, 33.7 mmol) and 1,1′-carbonyldiimidazole (6 g, 37 mmol) in THF (100 mL) was added. The mixture was stirred for 30 minutes at −78° C. and then warmed to −30° C. and stirred for 2 hours. The reaction was quenched with saturated NH4Cl, the phases were separated and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The residue was purified by silica gel chromatography eluted with 10% EtOAc in Toluene, which permitted the separation of the two diastereomers. Both isomers were obtained as an yellow solid with diastereomeric excess >95%.

1. customat −78° C.
2. additionwas added
3. stirringThe mixture was stirred for 30 minutes at −78° C.
4. temperaturewarmed to −30° C.
5. stirringstirred for 2 hours
6. customThe reaction was quenched with saturated NH4Cl
7. customthe phases were separated
8. extractionthe aqueous layer was extracted with EtOAc
9. washThe combined organic layers were washed with brine
10. dry with materialdried over Na2SO4
11. concentrationconcentrated
12. customThe residue was purified by silica gel chromatography
13. washeluted with 10% EtOAc in Toluene, which
14. customthe separation of the two diastereomers
15. customBoth isomers were obtained as an yellow solid with diastereomeric excess >95%