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Trangmolins A–F with an Unprecedented Structural Plasticity of the Rings A and B: New Insight into Limonoid Biosynthesis 下载免费PDF全文
Wanshan Li Prof. Dr. Li Shen Dr. Torsten Bruhn Dr. Patchara Pedpradab Prof. Dr. Jun Wu Prof. Dr. Gerhard Bringmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11719-11727
The absolute stereostructures of trangmolins A–F ( 1 – 6 ), limonoids with three new and one known topologies of the rings A and B, were unambiguously determined by NMR spectroscopic investigations, single‐crystal XRD analysis, and quantum‐chemical electronic circular dichroism calculations. Compounds 1 – 3 contain a hexahydro‐1H‐inden‐4‐one motif, compound 4 comprises a hexahydro‐2,6‐methanobenzofuran‐7‐one cage, and compound 5 consists of a hexahydro‐2H‐2,8‐epoxychromene scaffold. The C1?C30 linkage in 1 – 3 and the C3?C30 connection in 4 form two unprecedented types of ring A/B‐fused carbobicyclic cores: viii and ix . The oxidative cleavage of the C2?C3 bond in 5 and heterocyclization in 4 and 5 constitute the unprecedented tricyclic 6/6/5 ring A/B1/B2‐ and 6/5/6 ring A1A2/B‐fused topologies, respectively, which are uncovered, for the first time, in the construction of limonoid architectures. The diverse cyclization patterns of 1 – 6 reveal an unparalleled structural plasticity of rings A and B in limonoid biosynthesis. 相似文献
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Wei Cheng Dong Liu Fengying Zhang Qingying Zhang Patchara Pedpradab Peter Proksch Hong Liang Wenhan Lin 《Tetrahedron》2014
Chemical examination of a Chinese sponge Axinyssa sp. resulted in the isolation of 12 new formamidobisabolene-based analogues named axinyssines A–L (1–12), along with a new natural product (13) and three known formamidobisabolenes (14–16). Their structures were determined on the basis of extensive NMR and mass spectroscopic analyses in association with ICD data, Mosher reaction and chemical conversion for the assignment of absolute configurations. All compounds were evaluated for antitumor and antimicrobial activities. 相似文献
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