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NMR study of fumarprotocetraric acid, a complex lichen depsidone derivative from Cladonia furcata
Author(s) -
Su BaoNing,
Cuendet Muriel,
Nikolic Dejan,
Kristinsson Hördur,
Ingólfsdóttir Kristín,
van Breemen Richard B.,
Fong Harry H. S.,
Pezzuto John M.,
Kinghorn A. Douglas
Publication year - 2003
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.1181
Subject(s) - triethylamine , chemistry , double bond , proton nmr , derivative (finance) , stereochemistry , carbon 13 nmr , two dimensional nuclear magnetic resonance spectroscopy , organic chemistry , financial economics , economics
A lichen depsidone derivative, fumarprotocetraric acid, was obtained as the major constituent of Cladonia furcata (Huds.) Schrad. collected in Iceland. In the 1 H NMR spectrum (in DMSO‐ d 6 ) of this compound, the trans double bond proton signals of the fumaryl unit appeared as overlapping singlets. To confirm the presence of a trans double bond in the molecule, fumarprotocetraric acid was treated with triethylamine. The 1 H NMR spectrum of the resultant triethylamine salt displayed a pair of clear doublets with coupling constants of 15.7 Hz, which are characteristic of a trans double bond. Unambiguous 1 H and 13 C NMR spectral data for both fumarprotocetraric acid and its triethylamine salt were assigned for the first time based on the interpretation of their 2D NMR (HMQC, HMBC and NOESY) spectra. Copyright © 2003 John Wiley & Sons, Ltd.