Preparation of Highly Substituted Cyclohexene Systems

该项目的重点是环加成过程的发展，允许快速，高效地制备非常受阻的环己烯系统在高产率与优秀的非对映选择性。在弱刘易斯酸（AlMe 3）存在下使用强刘易斯酸（AlBr 3），其中AlMe 3作为酸清除剂，允许有效地使用酸不稳定官能团。丙二烯羧酸酯和甲硅烷基氧基二烯的[2+2]环加合物的简单形成和新颖的形式[3，3]-σ转移重排允许构建非常受阻的环己烯，那些有两个相邻的四元中心，在只有两个或三个步骤。新方法学将应用于四种具有生物活性的天然产物的合成，强心剂哇巴因，抗肿瘤化合物haterumaimide E，以及抗炎二萜类化合物hedychilactone B和hedychenone。加州-洛杉矶大学化学和生物化学系的Jung博士说。许多复杂的天然产物含有多取代的六元环作为其结构的组成部分，需要开发新的合成方法。Jung教授和他的学生正在研究新颖而有效的反应序列，从而可以精确控制三维结构来构建复杂的有机结构。复杂的有机结构通常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发展，这些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.