一种新型二肽甜味剂的合成及表征

Synthesis and Characterization of a Dipeptide Sweetener

摘要:

以3-环己基-L-丙氨酸、Boc-L-天冬氨酸-4-苄酯为原料合成二肽L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(I)，以3-羟基-4-甲氧基苯甲醛为原料经过Witting反应、H2还原和DIBAL-H还原三步反应合成3-羟基-4-甲氧基苯丙醛(II)，然后I与II在氢气、钯碳催化作用下进行还原氨化反应，得到目标产物N-[3-(3-羟基-4-甲氧基苯基)丙基]-α-L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(III)，总产率为50%。产物的结构采用IR、1HNMR、13CNMR和HRMS进行表征，并验证其甜度约为蔗糖的25000倍。合成终产物的最佳工艺条件为：n(II)：n(I)=1：1，Pd/C催化剂用量为反应物总重的10%，体积分数80%甲醇水溶液为溶剂，反应温度35 ℃，反应时间20 h。

Abstract:

The dipeptide sweetener N-[3-(3-Hydroxy-4-methoxyphenyl)propyl]-α-L-aspartyl-β-cyclohexyl-L-alanine-1-methyleste (III) was synthesized from 3-(3-hydroxy-4-methoxyphenyl)propanal (II) and a dipeptide (I) via a reductive amination reaction under an overall yield of 50%. The intermediate viz. 3-(3-hydroxy-4-methoxyphenyl)propanal (II) was prepared via a Witting reaction followed by a hydrogenation and a DIBAL-H reduction; while the dipeptide (I) was synthesized via a condensation of 3-cyclohexyl-L-alanine and Boc-L-aspartic acid-4-benzyl ester. The structure of product (III) was confirmed by IR, 1HNMR, 13CNMR and HRMS spectroscopic methods, and its sweetness was verified to be about 25000 times than sucrose. The optimum reaction conditions for the synthesis of product (III) were determined as follows: n(II):n(I)=1:1, the loading of Pd/C catalyst is 10% of the total weight of the reaction material in 80% methanol, the preferred reaction temperature was 40 ℃, and reaction time was 20 h.