作者:Philip R. Skaanderup、Robert Madsen
DOI:10.1021/jo020645c
日期:2003.3.1
An efficient strategy is described for the synthesis of enantiopure calystegine alkaloids. The key step employs a zinc-mediated fragmentation of benzyl-protected methyl 6-iodo-glycosides followed by in situ formation of the benzyl imine and Barbier-type allylation with zinc, magnesium, or indium metal. Stereochemistry in the pivotal allylation is controlled by the choice of the metal. The functionalized
描述了一种用于合成对映纯的卡司他汀生物碱的有效策略。关键步骤是用锌介导的苄基保护的甲基6-碘-糖苷片段化,然后原位形成苄基亚胺,并与锌,镁或铟金属进行Barbier型烯丙基化。关键的烯丙基化中的立体化学是通过选择金属来控制的。如此形成的官能化的1,8-壬二烯通过闭环烯烃复分解反应转化为环庚烯。区域选择性氢硼化和氧化得到相应的环庚酮,将其去保护得到所需的金刚烷基酯。由此,分别从D-葡萄糖,D-半乳糖和D-甘露糖制备卡来斯汀B(2),B(3)和B(4)。