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NMR studies on natural all‐ trans ‐(9′ Z ,11′ Z )‐(3 R ,3′ S ,5′ R ,6′ R )‐pyrrhoxanthin, an acetylenic C 37 ‐skeletal nor‐carotenoid butenolide
Author(s) -
Englert Gerhard,
Aakermann Torunn,
LiaaenJensen Synnøve
Publication year - 1993
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.1260311007
Subject(s) - homonuclear molecule , chemistry , pulse sequence , carbon 13 nmr satellite , chemical shift , carbon 13 nmr , stereochemistry , magnetization transfer , j coupling , heteronuclear molecule , coupling constant , nuclear magnetic resonance spectroscopy , proton nmr , nuclear magnetic resonance , crystallography , molecule , fluorine 19 nmr , physics , organic chemistry , medicine , particle physics , magnetic resonance imaging , radiology
Abstract All‐ trans ‐(9′ Z ,11′ Z )‐(3 R ,3′ S ,5′ R ,6′ R )‐Pyrrhoxanthin was isolated from a natural bloom of dinoflagellates (mainly Ceratium spp.) and submitted to detailed 1 H NMR and 13 C NMR analysis, including homonuclear COSY (2D), ROESY (1D and 2D), TOCSY (1D) and 1 H‐detected one‐bond and multiple‐bond 1 H, 13 C COSY. All chemical shifts and coupling constants in the 1 H NMR spectrum and all carbons in the 13 C NMR spectrum were assigned. The result is consistent with the structure, previously deduced, including relative configuration. A recently proposed variant of the ROESY pulse sequence, called T‐ROESY, claimed to suppress undesired TOCSY transfer, provided excellent results free of TOCSY artifacts caused by coherent magnetization transfer via J coupling pathways independent of the choice of the position of the carrier frequency.