Dicyclohexylcarbodiimide → HCID 131710222, compound

Participants

Reaction Steps

3.90 g (6 mmols) of H-Cys(Bzl)-Val-Leu-OH, 1.15TFA are dissolved in freshly distilled dimethylformamide, treated with 4.48 g (5.5 mmols) of BOC-Cys(Bzl)-Ser-Asn-Leu-Ser-Thr-OH and stirred at room temperature until all is dissolved. The solution is then cooled to 0°C, 1.26 g (11 mmols) of N-hydroxysuccinimide and 0.98 ml of triethylamine in 45 ml of dimethylformamide are added, followed by cooling to -22°C and the addition of 1.13 g (5.5 mmols) of dicyclohexylcarbodimide in 10 ml of dimethylformamide. The batch is stirred for 1 hour at -22°C, then at room temperature for 3 days, filtered to remove precipitated dicyclohexylurea, and evaporated to dryness. The residue is stirred twice with a mixture of 200 ml of ethyl acetate and 20 ml of 5% citric acid solution, then once with a mixture of 200 ml of ethyl acetate and 20 ml of 5% sodium bicabonate solution. The resulting product is filtered off and dried at 40°C in a high vacuum. Melting point: 218°-221°C; [α]D20 -28.5° (c = 2 in dimethylformamide); Rf8 = 0.43.

Provenance & Evidence