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Establishing Fungal Entomopathogens as Endophytes: Towards Endophytic Biological Control
Published on: April 11, 2013
(+)- and (-)-Alternarilactone A: Enantiomers with a Diepoxy-Cage-like Scaffold from an Endophytic Alternaria sp
Jian-Wei Tang1,2, Hou-Chao Xu1,2, Wei-Guang Wang1
1State Key Laboratory of Phytochemistry and Plant Resources in West China , Kunming Institute of Botany, Chinese Academy of Sciences , Kunming 650201 , Yunnan , People's Republic of China.
Abstract:
The enantiomers (+)- and (-)-alternarilactone A (1), the first examples of dibenzo-α-pyrones bearing a diepoxy-cage-like moiety, were isolated from the endophytic fungus Alternaria sp. hh930. The deficiency in 1H-1H COSY and HMBC correlations caused by the highly oxidized caged system of 1 and the deceptive and ambiguous signals such as "W" couplings in NMR data increased the risk of structure misassignment of 1. By performing a quantum chemical calculation of the NMR chemical shifts together with a DP4+ probability analysis and single-crystal X-ray crystallographic experiment, their structures were unambiguously determined, and their absolute configurations were determined by ECD calculations.
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