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Epikatonic acid from Austroplenckia populnea : structure elucidation by 2D NMR spectroscopy and X‐ray crystallography
Author(s) -
Silva G. D. F.,
Duarte L. P.,
Vieira Filho S. A.,
Doriguetto A. C.,
Mascarenhas Y. P.,
Ellena J.,
Castellano E. E.,
Cota A. B.
Publication year - 2002
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1009
Subject(s) - chemistry , crystal structure , hydrogen bond , molecule , crystallography , chloroform , two dimensional nuclear magnetic resonance spectroscopy , friedelin , stereochemistry , nuclear magnetic resonance spectroscopy , single crystal , intermolecular force , x ray crystallography , diffraction , organic chemistry , triterpenoid , physics , optics
From the chloroform extract of Austroplenckia populnea , epikatonic acid, friedelin, populnonic acid, abruslactone A, salaspermic acid and 22β‐epi‐maytenfolic acid were isolated. The structure and stereochemistry of epikatonic acid were established by two‐dimensional NMR spectroscopic techniques (HMQC, HMBC and NOESY) and later confirmed by single crystal X‐ray diffraction as 3β‐hydroxy‐olean‐12‐en‐29‐oic acid, which unambiguously established the configuration of the hydroxyl group at C‐3 as 3β‐OH and the carboxyl group at C‐20 as 20α‐COOH. The crystal structure shows two independent molecules in the asymmetric unit. The crystal packing is stabilized by four O–H·O intermolecular hydrogen bonds, which give rise to infinite double chains along the c axis. Copyright © 2002 John Wiley & Sons, Ltd.