Dicyclohexylcarbodiimide → HCID 13769326, compound

Participants

Reaction Steps

A suspension of Z-D-Ala-Gly-OMe (26) (5.88 g, 0.02 mmol) and 10% Pd-C (0.4 g) in methanol (300 ml) was stirred under a hydrogen atmosphere at room temperature for 1.5 hr. The catalyst was filtered and the filtrate was evaporated in vacuo. The residue and Z-Tyr (6.30 g, 0.02 mol) was dissolved in dry THF (300 ml), cooled to 0° C. and HOBt (2.70 g, 0.02 mol) and DCC (4.12 g. 0.02 mol) were added successively at 0° C. The solution was stirred for 3 hr at 0° C. and overnight at room temperature. The precipitated crystals were filtered. The filtrate was evaporated under reduced pressure, the residual crystals were dissolved in EtOAc and the solution was washed with 5% NaHCO3, 0.2 N Hcl and water, and dried over anhyd. Na2SO4. The solvent was removed in vacuo and the resulting solid was purified by silica gel column chromatography using CHCl3 --CH3OH (98:2) as eluant to give Z-Tyr-D-Ala-Gly-OMe (27) (8.62 g, 94.3%), mp 154°-155° C. (AcOEt-hexane); [α]D22 33.4° (C=1.0, MeOH); NMR (CDCl3 -DMSO-d6 (4:1) δ: 1.25 (3H, d, J=7 Hz, CH3), 2.82-3.03 (2H, m, CH2,), 3.70 (3H, s, CH3O), 3.80-3.95 (2H, m, CH2PhOH), 4.15-4.60 (2H, m, 2 CH), 5.05 (2H, s, CH2O), 6.70-7.25 (4H, m, ArH), 6.70-6.90 (1H, br, NH), 7.36 (5H, s, ArH), 7.70-8.10 (2H, br, NH). Rf (I)=0.48; Rf (VI)=0.08.

Provenance & Evidence