Regioselection Switch in Nucleophilic Addition to Isoquinolinequinones: Mechanism and Origin of the Regioselectivity in the Total Synthesis of Ellipticine
作者:Joaquim A. M. Castro、Bruno K. Serikava、Christian R. S. Maior、Fabrício F. Naciuk、Silvana A. Rocco、Carolina B. P. Ligiéro、Nelson H. Morgon、Paulo C. M. L. Miranda
DOI:10.1021/acs.joc.1c02952
日期:2022.6.17
Ellipticine was synthesized in six steps and 20% global yield starting from the readily available 2,5-dimethoxy isoquinoline. Unprecedented regioselective control of the nucleophilic attack on the isoquinoline-5,8-dione is first described. Investigation of the possible pathways of this transformation through density functional theory calculations reveals unexpected N-oxide assistance in cascade tautomerizations
从容易获得的 2,5-二甲氧基异喹啉开始,玫瑰树碱通过六个步骤合成,全球产率为 20%。首先描述了对异喹啉-5,8-二酮的亲核攻击的前所未有的区域选择性控制。通过密度泛函理论计算对这种转变的可能途径的研究揭示了在级联互变异构中意外的N-氧化物辅助,这对于指导亲核攻击和加速整个过程至关重要。使用这种策略,我们制备了苯胺-异喹啉二酮加合物并将其提交给分子内双 C-H 交叉偶联活化以提供玫瑰树碱,其在 MeLi 添加/BH 3还原序列后得到玫瑰树碱。