Halogenated C15 Acetogenin Analogues of Obtusallene III from a Laurenciella sp. Collected in Corsica

NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laboratory resulted in the identification of five new compounds (1–5) and 17 known compounds, among which 3-(E)-laurenyne represented by far the most abundant metabolite. Compounds 1 to 5 were isolated and fully characterized by detailed spectroscopic analysis. The absolute configuration and structural features of compound 1 were determined by single-crystal X-ray diffraction analysis. Compounds 1 to 4 are 12-membered cyclic ether acetogenins that are present in solution as interconverting conformers exhibiting an (aR) configuration of the bromoallene unit together with an S configuration at C-4. Among these, compound 3 is the first obtusallene derivative with bromine substituents at both the C-7 and C-12 positions. Compound 5 is an acetogenin bearing a [5.5.1]­bicyclotridecane ring system. A plausible biosynthetic route to 1–4 is proposed.本实验室开发的计算机辅助分析方法用于对Laurenciella属未定种菌株（Laurenciella sp.）开展核磁共振（NMR）化学指纹分析，最终鉴定得到5个新化合物（1~5）与17个已知化合物，其中3-(E)-劳伦炔（3-(E)-laurenyne）为占比最高的代谢产物。化合物1~5均通过细致的波谱分析完成分离与全结构表征。化合物1的绝对构型与结构特征通过单晶X射线衍射分析得以确定。化合物1~4均为12元环醚型聚酮乙酸酯类化合物（acetogenin），在溶液中以可相互转化的构象异构体形式存在，其溴代丙二烯单元具有(aR)构型，且C-4位为S构型。其中化合物3是首个在C-7与C-12位均带有溴取代基的obtusallene类衍生物（obtusallene）。化合物5为带有[5.5.1]双环十三烷（[5.5.1]bicyclotridecane）环系的聚酮乙酸酯类化合物（acetogenin）。本文提出了一条针对化合物1~4的合理生物合成途径。