Dicyclohexylcarbodiimide → HCID 57174957, compound

Participants

Reaction Conditions

Reaction Steps

24.5 g (0.087 mol) of N-benzyloxycarbonyl-L-valinal dimethyl acetal were dissolved in 200 ml of methanol and the solution was hydrogenated for 2 hours in the presence of 0.5 g of 5% palladium/carbon. After removal of the catalyst by filtration, the solvent was removed by evaporation and the residue was dissolved in 250 ml of dichloromethane. The solution was washed with brine and dried over magnesium sulphate. The solution was then cooled to -20° C. and there were then added 21.8 g (0.087 mol) of N-benzyloxycarbonyl-L-proline followed by 19.8 g (0.096 mol) of N,N'-dicyclohexylcarbodiimide. The solution was stirred at -20° C. for 2 hours and left to stand at 4° C. for 64 hours. The separated N,N'-dicyclohexylurea was removed by filtration and the filtrate was evaporated. The residue was taken up in ethyl acetate, the solution was washed with sodium bicarbonate solution and brine, dried over magnesium sulphate and evaporated to give an oil. The product was purified by chromatography on 250 g of silica gel using ethyl acetate/hexane (1:1) for the elution. Evaporation of the solution yielded 21.9 g (67%) of N-benzyloxycarbonyl-L-prolyl-L-valinal dimethyl acetal; Rf-value (ethyl acetate): 0.63.

Provenance & Evidence