Z-Lys(Boc)-Lys(Boc)-Pro-NH2 → Z-Lys(Boc)-Lys(Boc)-Lys(Boc)-Pro-NH2

Participants

Reaction Conditions

Reaction Steps

Compound XV (1.06 g, 1.5 mmoles) is hydrogenolyzed over palladium in methanol for 3 hours. After the solvent have been removed by evaporation in vacuo the residue is dissolved in ethyl acetate and chilled in an ice bath. To this is added Nα -benzyloxycarbonyl-Nε -t-butyloxycarbonyl-L-lysine N-hydroxy-succinimide (0.72 g, 1.5 mmoles) and the mixture is stirred at 4° C overnight. The precipitates which has separated are filtered off, washed with ice-cold ethyl acetate and dried in vacuo (1.31 g). An additional quantity of the product is obtained upon concentration of the filtrate (0.08 g). The combined precipitates are dissolved in methanol and most of the solvent is removed by evaporation in vacuo. The resulting sirupy residue is precipitated from ethyl acetate (20 ml)-ether (20 ml); yield 1.35 g (96%).

Provenance & Evidence