反应详情

N-Methyl morpholine (4.0 ml) and 1-ethyl-3-(3-dimethylaminopropyl) carbodimide (EDC) hydrochloride (0.96 g, 0.005 mole) were added to a solution of the product of Step B (1.76 g, 0.005 mole), methionine methyl ester hydrochloride (1.0 g, 0.005 mole) and 1-hydroxybenzotriazole hydrate (HOBT,0.677 g, 0.005 mole) in dimethylformamide (DMF, 30 ml) the reaction mixture was stirred at room temperature over the weekend, concentrated in vacuo and taken up in ice, water, and ethyl acetate. After addition of 10% aqueous citric acid, the ethyl acetate solution was separated, washed with water (2×), aqueous NaHCO3 and brine, and dried over sodium sulfate. Filtration and evaporation of the ethyl acetate solution gave a pale yellow residue, which was purified by column chromatography (silica gel) using 35% ethyl acetate-hexane. The title compound (1.97 g) was obtained as a white solid.

1. concentrationconcentrated in vacuo
2. additionAfter addition of 10% aqueous citric acid
3. customthe ethyl acetate solution was separated
4. washwashed with water (2×), aqueous NaHCO3 and brine
5. dry with materialdried over sodium sulfate
6. filtrationFiltration and evaporation of the ethyl acetate solution
7. customgave a pale yellow residue, which
8. customwas purified by column chromatography (silica gel)