Department of Chemistry, Faculty of Science, King Faisal University, P.O. Box 380, Al-Ahsa 31982, Saudi Arabia.
Nat Prod Rep. 2014 Sep;31(9):1088-100. doi: 10.1039/c4np00029c.
2,5-Disubstituted tetrahydrofurans constitute the core skeleton of several natural products and are pivotal synthetic analogues of medicinal importance that exhibit remarkable bioactivities. Oxasqualenoid natural products are implicated as potent biologically active molecules, particularly with regard to demonstrating significant cytotoxicity. Characteristic features of oxasqualenoids containing tetrahydrofuran fragments include the presence of a cis- and/or trans-2,5-disubstituted pattern in tetrahydrofuran moieties, and molecular symmetry is often noticed as well. Given their unique structural features combined with their bioactivity, two representative examples from this class of natural products, eurylene and teurilene, have been briefly reviewed. Eurylene, with reported cytotoxicity against lymphocytic leukemia, contains two non-adjacent linked cis- and trans-2,5-disubstituted tetrahydrofuran rings and a combined total of eight stereogenic centres. It is a chiral molecule due to the lack of a C2 axis of symmetry. Teurilene shows a prominent cytotoxicity on KB cells and has three adjacently linked 2,5-disubstituted tetrahydrofurans. A distinctive achiral facet is observed in teurilene, despite having eight stereocentres, due to the presence of meso symmetry (Cs). The prime objective of this account is to describe a precise mechanistic insight for both cis- and trans-2,5-disubstituted tetrahydrofurans present in these natural products and to highlight the exciting challenges encountered during the installation of functionalities or structural motifs en route to their synthetic approaches.
2,5-二取代的四氢呋喃是几种天然产物的核心骨架，也是具有重要药用价值的合成类似物的关键，具有显著的生物活性。氧杂螺戊烷类天然产物被认为是具有强大生物活性的分子，特别是在表现出显著的细胞毒性方面。含有四氢呋喃片段的氧杂螺戊烷类天然产物的特征包括四氢呋喃部分存在顺式和/或反式 2,5-二取代模式，并且通常也注意到分子对称性。鉴于它们独特的结构特征及其生物活性，本文简要综述了该类天然产物中的两个代表性例子，eurylene 和 teurilene。eurylene 对淋巴细胞白血病具有细胞毒性，含有两个不相邻的顺式和反式 2,5-二取代的四氢呋喃环和总共八个立体中心。由于缺乏 C2 对称轴，它是一个手性分子。teurilene 在 KB 细胞上表现出明显的细胞毒性，并且具有三个相邻连接的 2,5-二取代的四氢呋喃。尽管存在八个立体中心，但 teurilene 具有 meso 对称性 (Cs)，因此观察到一个独特的非手性方面。本文的主要目的是描述这些天然产物中顺式和反式 2,5-二取代的四氢呋喃存在的精确机制见解，并强调在其合成方法中安装功能或结构基序时遇到的令人兴奋的挑战。
