HCID 151180, compound → HCID 131722374, compound

Participants

Reaction Steps

6.5 g (18.0 mmol) of Z-Phe-D-Ala-OH was dissolved in 15 ml methanol and 2 ml formic acid. 0.2 g palladium catalyst was added and hydrogen was passed through the solution for 3 hours. The catalyst was removed by filtration, and the solvents were evaporated under vacuum. The residue was flooded with ether. The precipitate was filtered off, rinsed with ether and dried. The yield of H-Phe-D-Ala-OH was 5.3 g (98.1%). Rf=0.01 in chloroform:ethyl acetate:methanol:acetic acid=6:3:1:0.1. Rf=0.45 in acetic acid:chloroform:methanol=1:3:2:2. 8.0 g (15.0 mmol) of pentafluorophenyl ester of Boc-D-Orn(Z)-OPfp was dissolved in 15 ml dioxane. To this was added with mixing 4.3 g (17.7 mmol) H-Phe-D-Ala-OH dissolved in water with pH 8.5. The reaction mixture was stirred for a day and a night at room temperature. The solvents were evaporated under vacuum, 70 ml ethyl acetate was added, and the mixture was acidified to pH 2-3 by the addition of 2% sulfuric acid solution. The peptide was extracted twice with 70 ml ethyl acetate, washed with saturated sodium chloride solution to neutral pH and dried over anhydrous sodium sulfate. The solvent was removed by evaporation under vacuum leaving a thick oil. The product was crystallized from ethyl acetate with ether and hexane. The yield was 6.92 g (74.4%), and the melting point was 145° C. Rf=0.44 in acetic acid:chloroform;methanol=0.5:16:1. Rf=0.32 in chloroform:ethyl acetate:methanol=6:3:1.

Provenance & Evidence