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Total Syntheses of (−)‐Isoschizogamine and (−)‐2‐Hydroxyisoschizogamine
Author(s) -
Wang Xiaobei,
Xia Dongliang,
Tan Ling,
Chen Huan,
Huang Hongxiu,
Song Hao,
Qin Yong
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502869
Subject(s) - computer science
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.