p-Toluenesulfonic acid → Z-D-Lys(Boc)-Phe-D-Lys(Boc)-Phe-Gly-OMe

Participants

Reaction Steps

1.6 g of HOOBt, 1.3 g of NEM and 2.2 g of DCC are added to 5.3 g of Z-D-Lys(Boc)-Phe-OH and 6.4 g of H-D-Lys(Boc)-Phe-Gly-OMe, TosOH in 100 ml of DMF, with stirring. After the mixture has been left to stand overnight and the urea has been filtered off, the solvent is distilled off in vacuo. The residue is taken up in 300 ml of ethyl acetate/n-butanol (2:1), the mixture is washed, as above, with citric acid solution, sodium bicarbonate solution and water and dried over sodium sulfate and the solvent is distilled off in vacuo. The residue is recrystallized from 60 ml of isopropanol.

Provenance & Evidence