反应详情

温度

0 °C

Di-t-butyl bromomalonate (15.9 g.) was added to a stirred solution of L-alanyl-L-proline t-butyl ester (26 g.) in toluene (30 ml.) which was cooled to 0° C., and the mixture was allowed to warm up to laboratory temperature during 2 hours and was stirred at that temperature for 14 hours. Diethyl ether (300 ml.) was added, the mixture was filtered to remove unreacted L-alanyl-L-proline t-butyl ester as the hydrobromide salt thereof, andthe filtrate was evaporated to dryness under reduced pressure. The residue was dissolved in ethyl acetate (400 ml.) and the mixture was washed successively twice with aqueous 0.5N-citric acid solution (100 ml. each time), once with water (100 ml.) and once with saturated aqueous sodium chloride solution (100 ml.), dried over magnesium sulphate and evaporated to dryness under reduced pressure. The residue was purified by chromatography on a silica gel column using a 9:1 v/v mixture of dichloromethane and ethyl acetate as eluant, and there was thus obtained as an oil N-[di-t-butoxycarbonylmethyl]-L-alanyl-L-proline t-butyl ester.

1. temperatureto warm up to laboratory temperature during 2 hours
2. filtrationthe mixture was filtered
3. customto remove unreacted L-alanyl-L-proline t-butyl ester as the hydrobromide salt
4. customandthe filtrate was evaporated to dryness under reduced pressure
5. dissolutionThe residue was dissolved in ethyl acetate (400 ml.)
6. washthe mixture was washed successively twice with aqueous 0.5N-citric acid solution (100 ml
7. dry with materialeach time), once with water (100 ml.) and once with saturated aqueous sodium chloride solution (100 ml.), dried over magnesium sulphate
8. customevaporated to dryness under reduced pressure
9. customThe residue was purified by chromatography on a silica gel column
10. additiona 9:1 v/v mixture of dichloromethane and ethyl acetate as eluant