反应详情

Crude D-tryptophan benzyl ester (1.0 g, 3.40 mmol), 1-hydroxybenztriazole hydrate (0.63 g, 4.1 mmol) and t-butoxycarbonyl-α-methylalanine (0.84 g, 4.11 mmol) were stirred together at room temperature in chloroform (20 mL). 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (980 mg, 5.11 mmol) was added to this mixture in a single portion. The reaction mixture was stirred at room temperature for 4 hours and worked up by pouring into water (50 mL). The chloroform layer was separated and washed with 5% aqueous citric acid solution (25 mL) and 5% aqueous sodium bicarbonate solution (25 mL). The chloroform layer was dried over magnesium sulfate, filtered and evaporated under vacuum to afford a thick oily foam. Chromatography on silica gel using ethyl acetate/hexanes (2:3 v/v) afforded a yellow foam (0.822 g 50%).

1. customThe chloroform layer was separated
2. washwashed with 5% aqueous citric acid solution (25 mL) and 5% aqueous sodium bicarbonate solution (25 mL)
3. dry with materialThe chloroform layer was dried over magnesium sulfate
4. filtrationfiltered
5. customevaporated under vacuum
6. customto afford a thick oily foam
7. customafforded a yellow foam (0.822 g 50%)