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Complete Assignment of the 1H and 13C NMR Spectra of Flavone and its A-Ring Hydroxyl Derivatives

✍ Scribed by Dagfinn W. Aksnes; Arne Standnes; Øyvind M. Andersen

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
286 KB
Volume
34
Category
Article
ISSN
0749-1581

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✦ Synopsis

Complete assignment of the 'H and I3C NMR spectra of flavone and three flavone derivatives is reported. Protonproton and carbon-proton coupling constants of the flavones, including the extreme seven-bond long-range coupling between H-7 and H-3 in 6-hydroxyflavone (0.52 Hz) and flavone (0.27 Hz), are presented. Hydrogen bonding between 5-OH and the keto group (C-4) in 5,7-dihydroxyflavone gives rise to a large coupling constant between H-3 and C-3 (169.1 Hz), in addition to the expected low-field shifts of the 5-OH hydroxyl proton (12.92 ppm) and C-4 (181.86 ppm). This investigation revises the previously reported carbon assignments of three of the examined flavones and provides new NMR data for dhydroxyflavone.

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