Methanol → Benzyloxycarbonyl-asparagine

Participants

Reaction Conditions

Reaction Steps

3.36 g of Z-Ile-Ala-OH was catalytically reduced in a mixed solvent of 20 ml of methanol and 15 ml of water in the presence of palladium black. The resulting dipeptide was dissolved in 20 ml of water containing 1.4 ml of triethylamine and 16 ml of tetrahydrofuran and cooled to -10° C. To this solution was added a mixed acid anhydride obtained from 3.46 g of Z-Asn-OH, 1.67 ml of isobutyl chloroformate and 1.42 ml of N-methylmorpholine at -10° C. in a mixed solution of 15 ml of dimethylformamide and 20 ml of tetrahydrofuran. The reaction mixture was stirred at 0° C. for 5 minutes, then at 15° C. for 30 minutes followed by distilling off the solvent. To the residue was added 1 N citric acid, and a precipitate thus-formed was washed with water, dried, and reprecipitated from methanol-ethyl acetate to purify. Thus, there was obtained 3.60 g of the end product. m.p. 240°-244° C. (d.); [α]D19 : -13.8° (C: 1.0; dimethylformamide)

Provenance & Evidence