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NMR assignments of the major cannabinoids and cannabiflavonoids isolated from flowers of Cannabis sativa
Author(s) -
Choi Young Hae,
Hazekamp Arno,
PeltenburgLooman Anja M. G.,
Frédérich Michel,
Erkelens Cornelis,
Lefeber Alfons W. M.,
Verpoorte Robert
Publication year - 2004
Publication title -
phytochemical analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 72
eISSN - 1099-1565
pISSN - 0958-0344
DOI - 10.1002/pca.787
Subject(s) - chemistry , cannabidiol , cannabinol , carbon 13 nmr , stereochemistry , proton nmr , cannabinoid , chemical shift , carboxylic acid , organic chemistry , cannabis , receptor , psychology , biochemistry , psychiatry
The complete 1 H‐ and 13 C‐NMR assignments of the major Cannabis constituents, Δ 9 ‐tetrahydrocannabinol, tetrahydrocannabinolic acid, Δ 8 ‐tetrahydrocannabinol, cannabigerol, cannabinol, cannabidiol, cannabidiolic acid, cannavin A and cannavin B have been determined on the basis of one‐ and two‐dimensional NMR spectra including 1 H‐ and 13 C‐NMR, 1 H‐ 1 H‐COSY, HMQC and HMBC. The substitution of carboxylic acid on the cannabinoid nucleus (as in tetrahydrocannabinolic acid and cannabidiolic acid) has a large effect on the chemical shift of H‐1″ of the C5 side chain and 2′‐OH. It was also observed that carboxylic acid substitution reduces intermolecular hydrogen bonding resulting in a sharpening of the H‐5′ signal in cannabinolic acid in deuterated chloroform. The additional aromaticity of cannabinol causes the two angular methyl groups (H‐8 and H‐9) to show identical 1 H‐NMR shifts, which indicates that the two aromatic rings are in one plane in contrast to the other cannabinoids. For the cannabiavonoids, the unambiguous assignments of C‐3′ and C‐4′ of cannavin A and B were determined by HMBC spectra. Copyright © 2004 John Wiley & Sons, Ltd.