反应详情

Ac-Ser(Bzl)-Asp(OBzl)-Ala-Ala-OBzl (0.6 g, 0.888 mmol) was hydrogenated in a Parr apparatus at 50 psi in the presence of 0.62 g catalyst (5% Pd on BaSO4) in a solvent mixture consisting of 35 ml MeOH, 15 ml H2O, and 1 ml HOAc for 4 hours. The catalyst was filtered off and the filtrate concentrated to a smaller volume and lyophilized to give 0.38 g crude material. Tlc showed two minor contaminants in addition to the major component. The compound was then purified on a Bio-Rad AGl×2 column (3×24 cm) which was washed with 0.2 M NaOH, H2O, 0.2 M HOAc, and equilibrated with pH 8.5 buffer of 0.025 M ammonium acetate. The sample was applied at this pH and the column eluted with 250 ml each of the following acetic acid solutions in the order of: 0.25 M, 0.5 M, 1.0 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, and 4.5 M. The flow rate was adjusted to approximately 50 ml/hr and each 10 ml fraction was collected into an LKB fraction collector. The compound was located by spotting a 5 μl portion from each tube on silica get tlc plate (Merck 60, F-254) and developed in the solvent system of n-BuOH:HOAc:EtOAc:H2O (1:1:1:1) and then stained with chlorine-tolidine reaction. The fractions containing the major component were pooled and lyophilized twice to give 310 mg (86.3%) of the desired product; [α]D25 =-77.01° (c 1, 10% HOAc).

1. filtrationThe catalyst was filtered off
2. concentrationthe filtrate concentrated to a smaller volume
3. customto give 0.38 g crude material
4. additionin addition to the major component
5. customThe compound was then purified on a Bio-Rad AGl×2 column (3×24 cm) which
6. washwas washed with 0.2 M NaOH, H2O, 0.2 M HOAc
7. washthe column eluted with 250 ml each of the following acetic acid solutions in the order of: 0.25 M, 0.5 M, 1.0 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, and 4.5 M
8. customeach 10 ml fraction was collected into an LKB fraction collector
9. customget tlc plate (Merck 60, F-254)
10. additionThe fractions containing the major component