SYNTHESES OF CYCLOPENTANOID NATURAL PRODUCTS

复杂的环状天然产物的合成提供了动力 为开发新的和有效的方法， 环. 在过去的两年里，我们已经证明， 烯丙基硅烷与亲电子烯烃的分子内加成能够 产生大量的双环系统。 迄今 我们已经将这些发现用于立体特异性合成 倍半萜类化合物诺卡酮、维达醇和perforenone-A。 在这个提议中，我们将我们的成环方法应用于几个 天然存在的聚醌类化合物， 由于其新颖的结构和生物活性而备受关注。 的 这一建议的目的不仅仅是提出“新”的办法， “老”分子使用已知的化学;而是为了突出 我们的碳环化工艺具有独特的多功能性和优势。 我们对直链三喹烷类化合物hirsutene和capnellene的统一研究 利用了在环化反应中的非对映选择能力， 烯丙基硅烷 我们还提出了一种新的双环化方法，并打算 用它来建造一个共同的前体， 几种稠合三醌的有效合成及其生物活性 重要的萜烯并五烯内酯E和G;我们使用常见的 前体与其他已知策略的对比。

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.