反应详情

To a stirred solution of crude (3S,4S)-4-amino-N-butyl-3-(tertbutyldimethylsilyloxy)-5-cyclohexylpentanamide (311 mg, 0.81 mmol) in MeCN were added powdered NaHCO3 (203 mg, 2.43 mmol) and p-nitrophenyl chloroformate (244 mg, 1.21 mmol) and the mixture was stirred overnight at rt. The mixture was concentrated under reduced pressure. The residue was taken up in 1:1 EtOAc/Et2O (90 mL), washed with water (20 mL) and brine (20 mL), dried over MgSO4 and concentrated to leave an orange oil. This material was chromatographed on a 40-g silica cartridge eluted with a 0 to 100% ethyl acetate in hexanes gradient to afford 4-nitrophenyl (2S,3S)-5-(butylamino)-3-(tert-butyldimethylsilyloxy)-1-cyclohexyl-5-oxopentan-2-ylcarbamate (39 mg, 8%).

1. concentrationThe mixture was concentrated under reduced pressure
2. washwashed with water (20 mL) and brine (20 mL)
3. dry with materialdried over MgSO4
4. concentrationconcentrated
5. customto leave an orange oil
6. customThis material was chromatographed on a 40-g silica cartridge
7. washeluted with a 0 to 100% ethyl acetate in hexanes gradient