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Revised assignment of the 1 H NMR spectrum of the quinolizidine alkaloid lupinine
Author(s) -
Rycroft David S.,
Robins David J.,
Sadler Ian H.
Publication year - 1992
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.1260301306
Subject(s) - homonuclear molecule , chemistry , quinolizidine , two dimensional nuclear magnetic resonance spectroscopy , nuclear overhauser effect , stereochemistry , alkaloid , nuclear magnetic resonance spectroscopy , nmr spectra database , proton nmr , spectral line , organic chemistry , molecule , physics , astronomy
Abstract The 1 H NMR spectrum of the quinolizidine alkaloid lupinine was studied at 200 and 600 MHz. A full assignment of the 1 H signals was achieved by application of a variety of NMR techniques, including homonuclear 1 H NOE difference, 2D δ H /δ H COSY and direct δ C /δ H correlation experiments. This results in some changes to the current literature assignments; particularly important is the conclusion that the chemical shift difference between the equatorial (β) and axial (α) protons at C‐9 is negative (−0.47 ppm) rather than positive. The currently accepted assignment of the 13 C NMR spectrum has been confirmed by independent, and more direct, means.