Rapid and Enantioselective Synthetic Approaches to Germanicol and Other Pentacyclic Triterpenes
作者:Karavadhi Surendra、E. J. Corey
DOI:10.1021/ja802730a
日期:2008.7.1
routes to the key intermediate 2 for the synthesis of the pentacyclic triterpene germanicol 1 have been developed. In the first, the ( S)-epoxide of farnesyl bromide is transformed in just three steps to the tetracyclic intermediate 7, which is converted to chiral 2 by treatment with polyphosphoric acid. The second synthetic route to 2 involves the coupling of the ( S)-epoxide 8 with vinyl iodide 9 to give
已经开发了用于合成五环三萜锗烷醇 1 的关键中间体 2 的两条极短的合成路线。首先,法呢基溴的 (S)-环氧化物只需三个步骤即可转化为四环中间体 7,然后通过多磷酸处理将其转化为手性 2。2 的第二条合成路线涉及将 (S)-环氧化物 8 与乙烯基碘 9 偶联得到 10 和 10 的两阶段酸催化环化以形成 2。在这项工作的过程中,我们还发现了一个非常不寻常的分子内 1,5-质子从碳正离子转移到 CC 双键。(2)H-标记实验证实了该过程的细节。