4-Methylmorpholine → DCCI HOBt

Participants

Reaction Conditions

Reaction Steps

To a cold solution of Boc-Ser(Bzl)-Gln-Thr(Bzl)-Pro-Leu-Val-Thr(Bzl)-Leu-Phe-OH (XVII) (0.296g, 0.215 mmol) in DMF (3.5 ml), HOBt (0.07g, 0.43 mmol) was added, followed by DCC (0.049g, 0.236 mmol). The mixture was stirred for 1 hour at 0° C while pH 7 was maintained by addition of NMM. A pre-cooled solution of the tridecapeptide amine was added and the pH adjusted to 7-8 with NMM. Stirring was continued for 2 hours at 0° C and for 3 days at room temperature. The mixture was evaporated to a small volume and treated with 4% aq. NaHCO3. The crude precipitate was filtered and washed with H2O to neutral. After drying it was triturated repeatedly with boiling MeOH to produce a white powder, 0.452g (74% based on the tridecapeptide amine). Amino acid analysis (6N HCl-phenol, 110° C, 24 hr), Lys3.8, Asp2.03, Thr1.64, Ser0.83, Glu2.12, Pro1.00, Gly1.08, Ala2.07, Val1.06, Ile2.00, Leu1.96, Tyr0.99, Phe1.00. For elemental analysis a sample was freeze-dried from DMSO; mp sintered 283°-290° dec. [α]D25 -23.8° (c 0.5, DMSO). Anal. Calcd for C192H255N29O42 (3641.384): C, 63.33; H, 7.06; N, 11.16. Found: C, 61.16; H, 7.07; N, 10.96.

Provenance & Evidence