反应详情

(S)-2-[(S)-2-(tert-Butoxycarbonyl-methyl-amino)-propionylamino]-3-methyl-butyric acid benzyl ester (7 g, 18 mmol) and 1 M aqueous lithium hydroxide (40 mL, 40 mmol) was added to THF/MeOH/H2O (3:1:1; 200 mL) to give a yellow solution. The reaction mixture was stirred at rt overnight and then concentrated in vacuo. The residue was dissolved in water and then acidified to pH 2 using first 6 M and then 1 M aqueous HCl. The mixture was extracted with EtOAc. The organic layer was dried over Na2SO4 and concentrated in vacuo to give crude (S)-2-[(S)-2-(tert-butoxycarbonyl-methyl-amino)-propionylamino]-3-methyl-butyric acid (5.7 g) which was used directly in the next step without further purification, m/z=303 (M+H).

1. customto give a yellow solution
2. concentrationconcentrated in vacuo
3. dissolutionThe residue was dissolved in water
4. extractionThe mixture was extracted with EtOAc
5. dry with materialThe organic layer was dried over Na2SO4
6. concentrationconcentrated in vacuo