Triethylamine → (4S)-1-[(2S,3S)-3-(N2-t-Butoxycarbonyl-L-asparaginyl)amino-2-hydroxy-4-phenylbutyryl]-4-chloro-N-t-butyl-L-prolinamide

Participants

Reaction Steps

4.4 ml (31.4 mmol) of triethylamine were added, whilst ice-cooling, to a solution of 6.0 g (15.7 mmol) of (4S)-1-[(2S,3S)-3-amino-2-hydroxy-4-phenylbutyryl]-4-chloro-N-t-butyl-L-prolinamide [prepared as described in Preparation 21(b)] and 10.6 g (30.0 mmol) of the p-nitrophenyl ester of N2 -t-butoxycarbonyl-L-asparagine in 50 ml of dimethylformamide, and the resulting mixture was stirred for 3 days. At the end of this time, the reaction mixture was freed from the solvent by distillation under reduced pressure, and the residue was diluted with methylene chloride. The diluted solution was washed with a 5% w/v aqueous solution of citric acid, with a 1N aqueous solution of sodium hydroxide and with a saturated aqueous solution of sodium chloride, in that order, after which it was concentrated by evaporation under reduced pressure. The residue thus obtained was purified by column chromatography, using a 1:30 by volume mixture of methanol and methylene chloride as the eluent, to give 7.6 g of the title compound as a colorless powder, melting at 126°-132° C.

Provenance & Evidence