Asymmetric Synthesis of Bioactive Natural Products

描述（由申请人提供）：该项目旨在开发和实施新的策略，用于表现出有前途的生物活性的复杂天然产物的全合成。将在该资助下合成的目标结构是：1）角鲨烯合成酶抑制剂萨拉戈萨酸C; 2）抗生素帕塔霉素; 3）集落刺激因子诱导剂leustroducsin B。这三种结构独特的天然产物具有高水平的官能团和立体化学复杂性，使它们成为发现新反应的有吸引力的平台。拟议研究的一个基本原则是，碳骨架的建立必须与立体化学信息的引入相一致，以实现最大效率;因此，级联反应是预计合成路线的主要部分。该策略特别是寻求利用新开发的试剂：叔丁基二甲基甲硅烷基乙醛酸叔丁基酯的独特反应性。这是一种偶联试剂，其结合互补的亲核和亲电反应伴侣，通常具有对伴随碳骨架建立的立体中心的高水平立体控制。在每一个建议的合成，关键步骤是一个新的，机械引导的加聚反应，在一个单一的操作中引入了分子复杂性的显着部分。这些反应被配置为使得关键官能团以适当的氧化态引入，从而最大限度地减少浪费的下游操作。公共卫生相关性：在本研究中合成的靶向分子都表现出潜在的生物活性，这在小分子治疗剂的开发中具有重要意义。这些化合物的有效制备是任何未来生物医学应用的必要前提。

DESCRIPTION (provided by applicant): This project seeks to develop and implement new tactics for the total synthesis of complex natural products that exhibit promising biological activities. Targeted structures that will be synthesized under the aegis of this grant are: 1) zaragozic acid C, a squalene synthase inhibitor; 2) pactamycin, an antibiotic; 3) leustroducsin B, a colony-stimulating factor inducer. These three structurally unique natural products share a high level of functional group and stereochemical complexity that renders them attractive platforms for new reaction discovery. An underlying principle of the proposed research is that buildup of the carbon skeleton must coincide with introduction of stereochemical information for maximum efficiency; therefore, cascade reactions are a staple of the projected synthetic routes. The strategies in particular seek to harness the unique reactivity of a newly developed reagent: tert-butyl tert-butyldimethylsilyl glyoxylate. This is a coupling reagent that conjoins complementary nucleophilic and electrophilic reaction partners, often with high levels of stereocontrol for the stereogenic centers that are concomitantly built up with the carbon skeleton. In each proposed synthesis, the key step is a new, mechanistically guided poly-addition reaction that introduces a significant fraction of the molecular complexity in a single operation. The reactions are configured such that the key functional groups are introduced in the proper oxidation state, minimizing wasteful downstream operations. PUBLIC HEALTH RELEVANCE: The molecules that are targeted for synthesis in this study all exhibit potent biological activities that could hold significance in the development of small molecule therapeutics. The efficient preparation of these compounds is a necessary precondition for any future biomedical applications.