反应详情

To a 0° C. solution of 2-(S)-tert-butoxycarbonylamino-3-(4-nitrophenyl)-propionic acid and N-methylmorpholine (1.1 mL, 9.65 mmol) in DMF (10 mL) is added dropwise iso-butyl chloroformate (1.25 mL, 9.65 mmol). The mixture is stirred at 0° C. for 20 minutes after which NH3 (g) is passed through the reaction mixture for 30 minutes at 0° C. The reaction mixture is concentrated and the residue dissolved in EtOAc, washed successively with 5% citric acid, water, 5% NaHCO3, water and brine, dried (Na2SO4), filtered and concentrated in vacuo to a residue that is triturated with a mixture of EtOAc/petroleum ether to provide 2.2 g (74% yield) of the desired product as a white solid.

1. concentrationThe reaction mixture is concentrated
2. dissolutionthe residue dissolved in EtOAc
3. washwashed successively with 5% citric acid, water, 5% NaHCO3, water and brine
4. dry with materialdried (Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated in vacuo to a residue that
7. customis triturated with a mixture of EtOAc/petroleum ether