Preparation of Highly Substituted Cyclohexene Systems

这个项目的重点是开发环加成工艺，使之能够快速有效地制备高产率、高非对映选择性的受阻环己烯体系。在弱路易斯酸(AlMe3)的存在下使用强Lewis酸(AlBr3)，其中AlMe3充当酸清除剂，允许有效地利用酸不稳定的官能团。烯丙基羧酸酯和硅氧基二烯的[2+2]环加成物的简单形成和新颖的形式[3，3]-Sigmatroy重排使得仅用两到三步就可以构建非常受阻的环己烯，例如具有两个相邻的四元中心的环己烯。新的方法将被应用于四种生物活性天然产物的合成，强心剂哇巴因，抗肿瘤化合物haterumaimide E，以及抗炎二萜类化合物hedychiacone B和hedychenone。凭借这一奖项，有机和高分子化学计划支持加州大学洛杉矶分校化学和生物化学系的Michael E.Jung教授的研究。许多复杂的天然产物都含有多取代六元环作为其结构的组成部分，这就要求开发新的合成方法。Jung教授和他的学生正在研究新的和有效的反应序列，允许构建复杂的有机结构，并精确控制三维结构。复杂的有机结构往往在新药或新材料的开发中发挥关键作用，随着分子医学和纳米技术的技术发展，新药物或新材料将变得越来越重要。

This project is focused on the development of cycloaddition processes that allow the rapid and efficient preparation of very hindered cyclohexene systems in high yields with excellent diastereoselectivity. The use of a strong Lewis acid (AlBr3) in the presence of a weak Lewis acid (AlMe3), in which AlMe3 acts as an acid scavenger, allows acid-labile functional groups to be used efficiently. The simple formation and novel formal [3,3]-sigmatropic rearrangement of the [2+2] cycloadducts of allenecarboxylates and silyloxy dienes permits the construction of very hindered cyclohexenes, e.g., those with two contiguous quaternary centers, in only two or three steps. The new methodology will be applied to the syntheses of four biologically active natural products, the cardiotonic agent ouabain, the antitumor compound haterumaimide E, and the anti-inflammatory diterpenes hedychilactone B and hedychenone.With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Michael E. Jung, of the Department of Chemistry and Biochemistry at the University of California - Los Angeles. Many complex natural products contain polysubstituted six-membered rings as an integral part of their structure, demanding the development of new methods for their synthesis. Professor Jung and his students are studying novel and efficient reaction sequences allowing the construction of complex organic structures with precise control over three-dimensional structures. Complex organic structures often play critical roles in the development of new drugs or new materials that will be increasingly important as technological developments in molecular medicine and nanotechnology increase.