The first and asymmetric total synthesis of longeracinphyllin A, a hexacyclic Daphniphyllum alkaloid, has been accomplished. A tetracyclic intermediate was prepared through silver-catalyzed alkyne cyclization and Luche radical cyclization. A phosphine-promoted [3 + 2] cycloaddition reaction was exploited to construct the sterically congested E ringbearing vicinal tertiary and quaternary centers. The
首次和不对称全合成长叶皂甙 A,一种六环水蚤生物碱,已经完成。通过银催化炔烃环化和卢氏自由基环化反应制备了四环中间体。利用膦促进的 [3 + 2] 环加成反应来构建空间拥挤的 E 环,该环带有相邻的三级和四级中心。环戊烯酮基序是通过使用分子内 Horner-Wadsworth-Emmons 烯化组装而成的。Raney Ni 还原在后期从硫代酰胺前体中释放出叔胺。