Total Syntheses of Yingzhaosu A and of Its C(14)-Epimer Including the First Evaluation of Their Antimalarial and Cytotoxic Activities
作者:Alex M. Szpilman、Edward E. Korshin、Haim Rozenberg、Mario D. Bachi
DOI:10.1021/jo050074z
日期:2005.4.1
(aldehydoperoxide 7 and its complementary five-carbon atom unit 35) were linked through a Mukaiyama aldol reaction followed by in situ dehydration under mild buffered basic conditions. The carbonyl group in the resulting peroxidic enone 39 was stereoselectively reduced with either R-CBS catalyst (42b) to give, after in situ desilylation, yingzhaosu A (1) or with S-CBS catalyst (42a) its C(14)-epimer 40. The
天然抗疟剂应召素A(1)的分子结构特征在于2,3-二氧杂双环[3.3.1]壬烷系统(3a),烯丙基醇,均烯丙基醇和五个立体异构中心。在这里,我们报告了从8个步骤的总合成合成yingzhaosu A(1)和从(S)-柠檬烯(12)开始的7.3%的总产率。)。为了最大程度地发挥功效,通过多组分自由基多米诺骨牌反应构建了桥接的双环内过氧化物分子核心,该反应在一次操作中形成了五个键。另外,采用了与过氧化物功能的敏感性对强碱性和亲核试剂以及还原剂相容的反应方案。一个有趣的步骤涉及在过氧化物和醛官能团的存在下碳-碳双键的选择性加氢,得到过氧化醛7。两个主要的合成子(醛过氧化物7及其互补的五碳原子单元35)通过Mukaiyama aldol反应,然后在温和的缓冲碱性条件下原位脱水进行连接。用R -CBS催化剂(42b)立体选择性地还原所得过氧化物烯酮39中的羰基,得到原位甲硅烷基化反应后的映照素A(1)或S