Total Syntheses of (−)‐Isoschizogamine and (−)‐2‐Hydroxyisoschizogamine |
| |
| Authors: | Xiaobei Wang Dongliang Xia Ling Tan Huan Chen Hongxiu Huang Dr Hao Song Prof?Dr Yong Qin |
| |
| Institution: | Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041 (P. R. China) |
| |
| Abstract: | Total syntheses of (?)‐isoschizogamine and (?)‐2‐hydroxyisoschizogamine are described. The synthesis employs two asymmetric Michael additions to establish chiral centers at C7 and the quaternary carbon C20. Regioselective reduction of the methylthioiminium cation rather than the enamine generates an isoschizogamine‐type pentacyclic skeleton. Acidic hydrolysis of the isoschizogamine‐type intermediate in the absence of oxygen provides natural (?)‐isoschizogamine. Conducting the reaction in the presence of oxygen leads to a multistep oxidative hydrolysis cascade that affords unnatural (?)‐2‐hydroxyisoschizogamine. |
| |
| Keywords: | asymmetric total synthesis biogenetic pathway isoschizogamine Michael addition oxidative hydrolysis |
|
