反应详情

温度

-78 °C

NaHMDS (1.0M, 17 mL, 17 mmol) was added to a stirred solution of (4R,5S)-3-[3-(4-Chlorophenyl)-propionyl]-4-methyl-5-phenyl-oxazolidin-2-one (4.8 g, 14 mmol) in THF (200 mL) at −78° C. under N2. Stirred at −78° C. for 45 minutes and then Bromo-acetic acid tert-butyl ester (2.5 mL, 17 mmol) was added dropwise over 10 minutes. The solution was allowed to warm to −20° C. over 4 hours and then quenched with saturated aqueous NH4Cl. The product was extracted into EtOAc (2×300 mL), dried over Na2SO4, concentrated in vacuo and purified by column chromatography on silica (20% EtOAc/hexanes) to give (3S)-3-(4-Chlorobenzyl)-4-((4R,5S)-4-methyl-2-oxo-5-phenyl-oxazolidin-3-yl)-4-oxo-butyric acid tert-butyl ester (5.1 g, 80%.) 1H NMR (CDCl3, 400 MHz) δ 7.44-7.21 (9H, m), 5.45 (1H, d, J 7.3 Hz), 4.68-4.62 (1H, m), 4.51-4.42 (1H, m), 3.01 (1H, dd, J 13.0 and 6.2 Hz), 2.78 (1H, dd, J 16.7 and 10.6 Hz), 2.63 (1H, dd, J 13.2 and 9.0 Hz), 2.32 (1H, dd, J 6.7 and 4.3 Hz), 1.38 (9H, s), 0.89 (3H, d, J 6.6 Hz.)

1. temperatureto warm to −20° C. over 4 hours
2. customquenched with saturated aqueous NH4Cl
3. extractionThe product was extracted into EtOAc (2×300 mL)
4. dry with materialdried over Na2SO4
5. concentrationconcentrated in vacuo
6. custompurified by column chromatography on silica (20% EtOAc/hexanes)