Cyclopentannelation in Total Synthesis

描述：（由申请人提供） 已经提出了nakadomarin A和guanacastepene，其中不对称 环戊烷是关键步骤。Nakadomarin A已被分离出来， 在1997年从冲绳Amphimedon sp.海绵中分离出的一种生物合成相关的 但在结构上没有先例。它有一个相当 六个杂环和碳环的复杂桥接系统。是 在L1210试验中具有细胞毒性（IC 50 1.3 μ g/mL），显示出抑制活性 对细胞周期蛋白依赖性激酶4（IC 50 = 9.9 μ g/mL），并具有抗菌 和抗真菌活性。2000年从一种 一种来自哥斯达黎加一棵树的内生真菌，也有一个独特的碳骨架。 它对耐甲氧西林S.金黄色葡萄球菌（MRSA）和抗 耐万古霉素粪肠球菌（VREF）。绝对立体化学 这两种化合物的合成是有疑问的，所以全合成也将构成一个 结构的证明。这两种天然产物在结构上都是独特的， 它们可能通过不寻常的机制开展各自的活动。癌 和多重耐药人类病原体是公众关注的两个领域 健康 在全面综合的同时，我们将努力改进方法 这是在第一个供资周期制定的，并扩大了其范围。一 工作的长期目标是确定基本方法是否可以 适用于对映选择性合成具有连续 季碳原子。这仍然是合成中的一个难题。

DESCRIPTION: (provided by applicant) Brief enantioselective total syntheses of nakadomarin A and of guanacastepene have been proposed in which the asymmetric cyclopentannelation is the key step. Nakadomarin A, which has been isolated from an Okinawan Amphimedon sp. sponge in 1997 is biosynthetically related to the manzamines, but is structurally without precedent. It has a fairly complicated bridged system of six heterocyclic and carbocyclic rings. It is cytotoxic in the L1210 assay (IC50 1.3 microg/mL), shows inhibitory activity against cyclin dependent kinase 4 (IC50 = 9.9 microg/mL), and has antibacterial and antifungal activity. Guanacastepene, which was isolated in 2000 from an endophytic fungus from a tree in Costa Rica, also has a unique carbon skeleton. It is active against both methicillin-resistant S. aureus (MRSA) and against vancomycin-resistant Enterococcus faecalis (VREF). The absolute stereochemistry of both compounds is in doubt, so the total synthesis will also constitute a proof of structure. Both natural products are structurally unique, therefore they may exert their respective activities through unusual mechanisms. Cancer and multi-drug-resistant human pathogens are two areas of concern in public health. In parallel with the total syntheses we will work to improve the methodology which was developed during the first funding cycle, and expand its scope. A long-range goal of the work is to determine whether the basic method can be adapted for the enantioselective synthesis of compounds with contiguous quaternary carbon atoms. This is still a difficult problem in synthesis.