SYNTHESES OF CYCLOPENTANOID NATURAL PRODUCTS

复杂环状天然产物的合成提供了一种动力 开发新的和有效的方法，以使环化 戒指。在过去的两年里，我们证明了 烯丙基硅烷与亲电性烯烃的分子内加成是可能的 产生了数量惊人的双环体系。到目前为止 我们已经将这些发现用于立体特异性合成 倍半萜Nootkatone、Widdrol和穿孔烯酮-A。 在这个提案中，我们将我们的环形成方法应用于几个 天然存在的多喹烷，最近吸引了相当多的 由于其新颖的结构和生物活性而受到关注。这个 这项提议的目的不是简单地提出这些问题的“新”方法 使用已知化学物质的“旧”分子；但更确切地说，是为了突出 我们的碳环化程序所独有的多功能性和优势。 直链三喹烷毛状烯和戊二烯的统一方法 在环化过程中利用非对映选择的能力 烯丙基硅烷。我们还提出了一种新的双环过程，并打算 使用它来构建公共前驱，从而允许 几种稠合三喹烷的高效合成及其生物活性 重要的倍半萜戊烯内酯E和G；我们常用的 前体与其他已知的策略形成了对比。

The synthesis of complex cyclic natural products has provided an impetus for the development of new and efficient methods for the annulation of rings. During the past two years we have demonstrated that the intramolecular addition of allylsilanes to electrophilic olefins is capable of producing a remarkably large number of bicyclic ring systems. To date we have utilized these findings in stereospecific syntheses of the sesquiterpenes nootkatone, widdrol, and perforenone-A. In this proposal we apply our method for ring formation to several of the naturally occurring polyquinanes which of late have attracted considerable attention because of their novel structures and biological activities. The object of this proposal is not simply to present "new" approaches to these "old" molecules using known chemistry; but rather to highlight the versatility and advantages unique to our carbocyclization procedures. Our unified approach to the linear-triquinanes hirsutene and capnellene exploits the capability for diastereoselection in the cyclization of allylsilanes. We also propose a novel bis-annulation process and intend to use it for the construction of a common precursor which permits the efficient synthesis of several fused-triquinanes and the biologically important sesquiterpenes pentalenolactone E and G; our use of a common precursor contrasts with other known strategies.