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Cajuputones A–C, β ‐Triketone Flavanone Hybrids from the Branches and Leaves of Melaleuca cajuputi
Author(s) -
Xu WenJun,
Xie Xin,
Wu Lin,
Tian XiaoMeng,
Wang ChengCheng,
Kong LingYi,
Luo Jun
Publication year - 2020
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.202000706
Subject(s) - chemistry , flavanone , stereochemistry , circular dichroism , vibrational circular dichroism , moiety , pyran , absolute configuration , organic chemistry , flavonoid , antioxidant
Three new β ‐triketone flavanone hybrids, cajuputones A–C were obtained from Melaleuca cajuputi (the Australian ‘tea tree’). The structures of cajuputones A–C were elucidated by 1D/2D NMR spectroscopy and HR‐ESI‐MS analyses; and their absolute configurations were established by electric circular dichroism (ECD) calculations using TDDFT method. Structurally, cajuputones A–C feature a rare 6/6/6/6 oxatetracyclic ring system fused between an acylphloroglucinol‐derived β ‐triketone and a pinocembrin or strobopinin moiety via an angle‐type pyran‐like motif. DFT‐based conformational optimization in chloroform explained the similarity of the 1D NMR data of cajuputones B and C (C‐2 epimers).