| 摘要 |
PURPOSE:To obtain the titled compound in high purity, by reacting an alpha-[3- substituted-5-oxoxadiazolidinyl-(4)]-acetic acid with a phenylalanine ester and heating the resultant novel composite crystal of both components in the absence of solvent or in a solvent. CONSTITUTION:A compound of formula I (R is organic residue which can be reducibly substituted with hydrogen) is made to react with a compound of formula II (R<1> is 1-4C alkyl) at 0-30 deg.C, preferably 7-25 deg.C to obtain a novel composite crystal of formula III in high purity. The crystal is heated as it is at >=120 deg.C, preferably about 120-130 deg.C or is dissolved in a solvent and heated at 20-70 deg.C, preferably 30-50 deg.C to obtain the objective compound of formula IV in high purity. Successive reduction of the compound with hydrogen gives alpha-aspartyl-phenylalanine ester useful as a low-calorific sweetener and, accordingly, the process is suitable as a method for the industrial production of said compound.
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