Enantioselective Annulation Using Nazarov Reagent: Synthesis of (+)-Preoleanatetraene
作者:Alejandro F. Barrero、Simeón Arseniyadis、José F. Moral、M. Mar Herrador、Antonio Rosellón
DOI:10.1055/s-2005-864798
日期:——
The enantioselective synthesis of preoleanatetraene (1) has been accomplished via a convergent approach of two C-15 synthons. The key step of this synthesis has been an interesting enantioselective variant of the Robinson annulation using the Nazarov reagent and a chiral enamine to obtain the bicyclic moiety A. This asymmetric methodology opens the access to other irregular triterpene skeletons whose biogenetic implication should not be underestimated.
预奥利烯四烯(1)的对映选择性合成已通过两种C-15合成单元的汇聚性方法完成。该合成的关键步骤是使用奈萨洛夫试剂和手性烯胺进行的一种有趣的对映选择性罗宾逊环化反应,以获得双环结构A。这种不对称方法学为其他不规则三萜骨架的获取提供了可能,其生物合成的意义不容小觑。