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Structural Elucidation and Total Synthesis of Three 9‑Norlignans from Curculigo capitulata

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journal contribution
posted on 20.03.2019, 00:00 authored by Song Li, Jin-Hai Yu, Yao-Yue Fan, Qun-Fang Liu, Zhan-Chao Li, Zhi-Xiang Xie, Ying Li, Jian-Min Yue
Capitulactones A–C, three unprecedented 9-norlignans featuring a unique 3,5-dihydrofuro­[2,3-d]­oxepin-7­(2H)-one scaffold, were isolated from the roots of Curculigo capitulata. Their structures with absolute configurations were unambiguously established by a combination of spectroscopic data, ECD analysis, and total synthesis. Biomimetic total syntheses of three pairs of the corresponding enantiomers were achieved in 9–10 steps with overall yields of 14.8, 12.7, and 10.3%, respectively. Notably, the unique scaffold of the common western hemisphere of the molecules was constructed by using the oxidation–reduction strategy from benzodihydrofuran.