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Further Withaphysalin Derivatives from Acnistus arborescens
Author(s) -
Maia Ana Isabel V.,
BrazFilho Raimundo,
Silveira Edilberto R.,
de Simone Carlos Alberto,
Pessoa Otília Deusdênia L.
Publication year - 2012
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201100386
Subject(s) - chemistry , heteronuclear single quantum coherence spectroscopy , stereochemistry , lactone , carbon 13 nmr , two dimensional nuclear magnetic resonance spectroscopy
Two new epimeric chlorinated withaphysalins, rel ‐(4 β ,5 β ,6 α ,18 S ,22 R )‐ and rel ‐(4 β ,5 β ,6 α ,18 R ,22 R )‐6‐chloro‐18,20‐epoxy‐18‐ethoxy‐4,5‐dihydroxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone ( 1 and 2 resp.), together with the new rel ‐(4 β ,5 β ,6 α ,18 R ,22 R )‐6‐chloro‐18,20‐epoxy‐4,5‐dihydroxy‐18‐methoxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone ( 3 ) and rel ‐(3 β ,4 β ,5 β ,6 β ,18 R ,22 R )‐5,6:18,20‐diepoxy‐3,18‐diethoxy‐4‐hydroxy‐1‐oxowith‐24‐ene‐26,22‐lactone ( 4 ) were isolated from the leaves of Acnistus arborescens and named withaphysalins T–W, respectively. The final structures and the complete 1 H‐ and 13 C‐NMR assignments of the three chlorowithaphysalins 1 – 3 were performed by means of HR‐ESI‐MS and 1D‐ and 2D‐NMR experiments, including COSY, HSQC, and HMBC, beside comparison with spectral data of analogous compounds from the literature. The structure of 4 was also confirmed by means of a single‐crystal X‐ray diffraction analysis.