sugar to the C5‐OH group of the macrocyclic aglycone of aldgamycin N is most difficult, if not even impossible, the synthesis route was revised and the glycosidation performed at an earlier stage. To mitigate the “cost” of this strategic amendment, a practical and scalable de novo synthesis of this branched octose was developed. The glycoside formation required mild conditions; it commenced with the reaction
由于随附的研究表明,将同名的阿德加糖引入阿德霉素 N 大环苷元的 C5-OH 基团是最困难的,甚至是不可能的,因此修改了合成路线,并在早期阶段进行了糖苷化。为了降低这一战略修改的“成本”,开发了这种支链八糖的实用且可扩展的从头合成。糖苷的形成需要温和的条件;它始于糖苷配基与三
氯乙
酰亚胺酯供体的反应,产生瞬时原酸酯,该原酸酯缓慢重排为所需的
吡喃糖苷。产品中极性外围基团的存在并不妨碍大环内酯环本身的选择性后期官能化:通过
钌催化的反式氢化
锡化,所含的炔
丙醇实体很容易转化为目标的特征性偶姻基序。通过改进的 Chan-Lam 型联轴器。