NATURAL PRODUCTS VIA CATIONIC CASCADE ANNULATIONS

最近在这些实验室的研究表明，阳离子 由酰基氮杂环丁烷离子和表锍离子引发的环化反应 代表了异常强大的方法， 复杂的环状系统 酰基亚硝基阴离子引发的环化反应不仅 允许不饱和氮杂环的快速构建，但也导致 周边2-酰基部分的同时安装。 表锍 (and episelenonium）诱导的碳环化已被证明是相当 一般的范围，并导致了结构复杂的合成 含可操作官能团的环体系 (e.g., ArS或ArSe部分）。 这项资助申请中提出的研究涉及 这些新的合成方法的应用，以制备选定的 天然目标结构。 这项研究的明确目标将是 探讨这些新方法的范围和局限性， 全合成 以这种方式，这些反应的实用性， 将展示操作上实用的化学合成。

Recently studies in these laboratories have revealed that cationic cyclizations initiated by acylnitrilium ions and episulfonium ions represent unusually powerful methods for the convergent elaboration of complex ring systems. Acylnitrilium ion initiated cyclizations not only permit the rapid construction of unsaturated azacycles but also result in the concurrent installation of peripheral 2-acyl moieties. Episulfonium (and episelenonium) induced carboannulations have proven to be quite general in scope and have led to the synthesis of structurally intricate ring systems with the net incorporation of a manipulable functional group (e.g., an ArS or ArSe moiety). The research proposed in this grant application is concerned with the application of these new synthetic methods to the preparation of selected natural target structures. The explicit goals of this research will be to probe the scope and limitations of these new methods in the context of total synthesis. In this way, the utility of these reactions for performing operationally practical chemical syntheses will be revealed.