N- formyl aspartyl way to manufacture the aspartyl phenylalanine methyl ester from phenylalanine methyl ester and oxalic acid salt of aspartyl phenylalanine methyl ester

摘要

The invention relates to a process for the preparation of aspartylphenylalanine methyl ester from N-formylaspartylalanine methyl ester by treatment with an acid, characterized in that N-formylaspartylalanine methyl ester is treated at 30-60 &loz& C with at least 0.5 molar equivalent oxalic acid per mole of N-formyl-aspartylphenylalanine methyl ester in a solvent mixture in which N-formylaspartylphenylalanine methyl ester dissolves well and in which the oxalic acid salt of aspartylphenylalanine methyl ester is poorly soluble, after which the oxalic acid salt of aspartylphenylalanine methyl ester is removed by filtration, dissolved in water and subsequently neutralized with the aid of an inorganic base with formation of free aspartylphenylalanine methyl ester.