NATURAL PRODUCTS VIA CATIONIC CASCADE ANNULATIONS

最近，这些实验室的研究表明，阳离子 酰基腈离子和环硫离子引发的环化反应 代表了非常强大的方法，用于收敛精化 复杂的环系。酰基氮离子引发的环化反应不仅 允许快速构建不饱和氮杂环，但也会导致 外周2-酰基部分的同时安装。淫羊藿苷 (和episelenonium)诱导的碳环已被证明是相当 在范围上是一般的，并导致了结构复杂的 含有可操控官能团的环状体系 (例如，ARS或屁股部分)。 在这项拨款申请中建议的研究涉及 这些新的合成方法在选择性合成中的应用 自然的目标结构。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。通过这种方式，这些反应对 操作实用的化学合成将被揭示。

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.