中文摘要：

（S）-4-氨基-5-巯基戊酸（Glutamate thiol,Glu SH）是谷氨酸α-羧基被亚甲基巯基取代的衍生物,也可被视为半胱氨酸的衍生物.该氨基酸是海洋抗肿瘤环酯肽Apratoxin E及其结构优化物的重要组成片段.报道（S）-4-氨基-5-巯基戊酸两种简便合成方法.第一种方法是以巯基和氨基均被保护的D-半胱氨酸为原料,先与米氏酸缩合生成β-酮酯,然后还原消除酮羰基、脱羧形成内酰胺,最后去除巯基和氨基上的保护基以及将内酰胺环打开,以4步76.0%的总收率得到所需产物.第二种方法以氨基和γ-羧基被保护的谷氨酸为原料,先将α-羧基还原为伯醇,然后借助Mitsunobu反应引入巯基,最后一锅脱除氨基、巯基和羧基上的保护基得到（S）-4-氨基-5-巯基戊酸.

英文摘要：

（S）-4-Amino-5-mercaptopentanoic acid（glutamate thiol, Glu SH） is a derivative of glutamic acid with α-carboxyl group substituted by methanethiol group. Meanwhile, it could be considered as a derivative of cysteine. This amino acid is an important fragment of marine cytotoxic cyclic depsipeptide apratoxin E. Two facile synthetic methods of（S）-4-amino-5-mercaptopentanoic acid are described. For the first strategy, protected D-cysteine derivate was used as starting material. After coupled with Meldrum s acid, the resulting β-keto ester underwent reductive elimination and thermal decarboxylative ring closure to afford 5-substituted pyrrolidinone（γ-lactam）. After removal of protecting groups and ring-open, the target compound was obtained in 76.0% overall yield. For the second method, commercial available Boc-Glu（OBzl）-OH was used as starting material. The thiol group was introduced by Mitsunobu reaction after converting the carboxylic acid to its corresponding alcohol. Then the protecting groups of amino, thiol, and carboxylic acid were removed smoothly in one pot to yield（S）-4-amino-5-mercaptopentanoic acid.