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Bipolarolides A–G: Ophiobolin‐Derived Sesterterpenes with Three New Carbon Skeletons from Bipolaris sp. TJ403‐B1
Author(s) -
Liu Mengting,
Sun Weiguang,
Shen Ling,
He Yan,
Liu Junjun,
Wang Jianping,
Hu Zhengxi,
Zhang Yonghui
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201905966
Subject(s) - chemistry , stereochemistry , pentadecane , nonane , circular dichroism , methylene bridge
Bipolarolides A–G ( 1 – 7 ), seven novel ophiobolin‐derived sesterterpenes with three new types of skeletons, were characterized from fungus Bipolaris sp. TJ403‐B1. Their structures were determined via spectroscopic analyses, X‐ray crystallography, and quantum chemical 13 C NMR and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 were uniquely defined by a multicyclic caged oxapentacyclo[9.3.0.0 1,6 .0 5,9 .1 8,12 ]pentadecane‐bridged system. Compounds 3 and 4 featured an unprecedented 5‐5‐5‐5‐fused core skeleton, while 3 also contained an unexpected C‐3–C‐14 oxygen bridge to construct the caged architecture. Compounds 5 – 7 form a new class of highly modified pentacyclic oxaspiro[4.4]nonane‐containing sesterterpene‐alkaloid hybrids. Their biosynthetic pathways and potential HMG‐CoA reductase inhibitory and antimicrobial activities are also discussed.