School of Chemistry, The University of Nottingham, University Park, UK.
Nat Prod Rep. 2011 Jul;28(7):1269-310. doi: 10.1039/c1np00023c. Epub 2011 Jun 3.
Macrocyclic and polycyclic ‘cembranoid’ diterpenes are one of the most widespread groups of natural products that are found in the marine milieu. The macrocyclic cembranoids are linked to each other by a network of oxygenation processes, which often climax with the formation of furano- and furanobutenolide-based macrocyclic cembranoids commonly found in gorgonian and soft corals. These macrocycles are then prone to oxidative rearrangements, photochemical ring contraction, and transannular cyclisations amongst others, leading to a plethora of novel and architecturally attractive marine metabolites. Although there is a dearth of knowledge about the enzymes that trigger some of the steps in their biosynthesis, speculations are rife. In this personal perspective we have examined many of the structural relationships within oxycembranoids and their relatives isolated from corals. This has allowed us to speculate on the likely biosynthetic interrelationships between structurally similar metabolites, and then propose some likely key carbon-to-carbon bond forming reactions that are followed in vivo in linking macrocyclic cembranoids to their polycyclic congeners. Biomimetic synthesis studies, which vindicate some of the biosynthetic speculations, are interweaved in the discussion.
大环和多环“cembranoid”二萜是在海洋环境中发现的分布最广泛的天然产物之一。大环cembranoids 通过一系列的氧化过程相互连接，这些过程通常以呋喃和呋喃丁烯内酯为基础的大环cembranoids 的形成达到高潮，这些化合物通常存在于柳珊瑚和软珊瑚中。这些大环化合物容易发生氧化重排、光化学环收缩和环间环化等反应，导致大量新颖的、结构吸引人的海洋代谢物的产生。尽管对于触发它们生物合成某些步骤的酶知之甚少，但有很多推测。在这篇个人观点中，我们检查了从珊瑚中分离出的 oxycembranoids 和它们的同系物的许多结构关系。这使我们能够推测结构相似的代谢物之间可能的生物合成相互关系，然后提出一些可能的关键碳-碳键形成反应，这些反应在体内将大环cembranoids 与其多环同系物连接起来。生物模拟合成研究验证了一些生物合成推测，这些研究交织在讨论中。
