Abstract: Tripeptide L-prolyl-L-leucyl-glycinamide (PLG) has important physiological and pharmacological functions，and can be used to treat Parkinson’s disease. PLG was synthesized by using the mixed anhydride method from L-proline，L-leucine and glycinamide. The amino groups of L-proline and L-leucine were protected firstly by the carbobenzoxy group，and then the carbobenzoxy group was removed by Pd/C with H2 from L-cbz-prolyl-L-leulyl-gly -NH2 to produce PLG in the end. Isobutyl chloroformate was used as reagent to form mixed anhydride. The optimum conditions to synthesize L-cbz-pro and L-cbz-prolyl- L-leu，were n(cbz)/n(L-pro)=2.6:1 at －5 ℃ for 2 hours and n(i-C4H9OCOCl)/n (L-cbz-pro)=1:1 at －10 ℃ respectively. Under these conditions，the melting point，optical purity and total yield of PLG were 120～122 ℃，98.7% and 38.5% respectively. The specific rotation [α]D20 was －46.3°。

摘要： L-脯氨酰-L-亮氨酰-甘氨酰胺三肽，具有重要的生理药理作用，可用于治疗帕金森病。以L-脯氨酸、L-亮氨酸和甘氨酰胺为原料，采用混合酸酐法，以苄氧羰基（cbz）为氨基保护基，以氯甲酸异丁酯为成酸酐试剂，以Pd/C催化氢解脱除cbz基合成了L-脯氨酰-L-亮氨酰-甘氨酰胺三肽，并进一步优化了合成条件：L-cbz-pro的最佳工艺条件为n(cbz)/n(L-pro)=2.6/1，反应温度－5 ℃，反应时间2 h；L-cbz-prolyl-L-leu的最佳工艺条件为，反应温度－10 ℃。在上述工艺条件下产品总收率38.5％，光学纯度98.7％，熔点 120～122 ℃，[α]D20=－46.3°。