application of both Schmidt and Yu glycosylations, the first total syntheses of the echinocystic acid saponins pithedulosides D and E, the two antitumoral and representative D-ring-functionalized oleanane-type saponins, were achieved. Benefitting from the applied convergent synthetic strategy, the echinocystic acids could be synthesized in overall yields of as high as 71 and 76 % through four linear steps
借助Schmidt和Yu糖基化的精心设计应用,实现了棘皮囊
藻酸皂苷pithedulosides D和E的首次全合成,这两个抗肿瘤和具有代表性的D环功能化的齐墩果烷型
皂苷。得益于所应用的收敛性合成策略,通过四个线性步骤可以合成棘孢囊酸,其总收率高达71%和76%。