A short synthetic route to polyhydroxylated spirocyclic glucose-based l-proline analogues is described from easily prepared 2,3,4,6 tetra-O-benzyl-d-glucono-lactone. The synthesis involves C-glycosylation of an exocyclic glucose-based epoxide with allyltributylstannane that affords functionalized C-ketosides containing an α-hydroxy ester moiety. Oxidation of the alcohol function, followed by stereoselective reductive amination provides an amine that undergoes iodine-induced aminocyclization to provide spirocyclic glucose-proline hybrids bearing an iodomethylene side-chain. The iodo function of the side-chain can be converted into other functional groups such as ester and hydroxyl groups, thereby allowing additional modifications to the pyrrolidine ring.
本文描述了一条简短的合成路线,用于制备基于
葡萄糖的多羟基化螺环
L-脯氨酸类似物,原料为易于制备的2,3,4,6四-O-苄基-
D-古洛糖酸内酯。合成过程包括利用外环
葡萄糖基
环氧化物与
烯丙基三丁基锡烷进行C-糖基化反应,生成含α-羟基酯基团的官能化C-酮糖苷。随后对醇功能进行氧化,再经立体选择性还原胺化得到胺,此胺在
碘诱导下发生胺环化,形成带有
碘甲叉侧链的螺环
葡萄糖-脯
氨酸杂化物。侧链上的
碘功能可转化为酯、羟基等其他功能基团,从而允许对
吡咯烷环进行进一步修饰。