Chlotrichenes A and B, Two Lindenane Sesquiterpene Dimers with Highly Fused Carbon Skeletons from Chloranthus holostegius

• DOI: 10.1021/acs.orglett.8b04046
• Publication Date: 2019-01-17T14:32:10Z
• Authors: Jun Chi; Wenjun Xu; Shanshan Wei; Xiaobing Wang; Jixin Li; Hongliang Gao; Lingyi Kong; Jun Luo
• Keywords: Models, Molecular; Magnoliopsida; Molecular Conformation; Dimerization; Sesquiterpenes; 01 natural sciences; Carbon; 0104 chemical sciences

Two unprecedented lindenane sesquiterpene dimers, chlotrichenes A (1) and B (2), were obtained from Chloranthus holostegius var. trichoneurus. Their structures were characterized by NMR, ECD, and X-ray diffraction analysis. They possess a new type of spirocarboncyclic dimeric framework formed by endo-Diels-Alder reaction, and the structure of 1 features a unique 3/5/6/6/6/6/5/3-fused octacyclic skeleton by subsequently plausible epoxidation-cyclization reactions of 2. Compound 2 showed synergetic cytotoxicity with DOX on U2 OS cells (CI: 0.94 ± 0.03).