The diastereoselecetive and scalable synthesis of cyclic guanidine-containing nonproteinoginic amino acids, enduracididines, has been achieved. Both diastereomers, l-allo-enduracididine and l-enduracididine, were prepared via catalyst-controlled asymmetric nitroaldol reaction with the aldehyde precursor derived from l-aspartic acid. The cyclic guanidine of di-Cbz-protected l-allo-enduracididine was fully protected with an allyl group to suppress nucleophilic side reactions. Introduced allyl group was efficiently removed via π-allylpalladium chemistry without attaching the Cbz group on the cyclic guanidine moiety.

中文翻译：

---

通过不对称硝基醛醇缩醛立体选择性合成保护的l-allo-Enduridineidine和l-Enduridineidine

已实现了含环胍的非蛋白氨基酸氨基酸（非尿苷）的非对映选择性合成。非对映体两者，升-同种异体-enduracididine和升-enduracididine，分别经由与衍生自醛的前体催化剂控制的不对称硝基醛醇反应制备升天冬氨酸。二Cbz-保护的环状胍升-同种异体-enduracididine内部进行充分的烯丙基抑制亲核的副反应的保护。引入的烯丙基通过π-烯丙基铝化学方法有效地除去，而没有在环胍部分上连接Cbz基团。