2008•Magnetic Resonance in ChemistryRequires access

Empirically predicted 13C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone

Raymond Evans March, Darcy C. Burns, David A. Ellis

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Abstract

8-Hydroxyflavone is not found in nature. While the (13)C chemical shifts of 8-hydroxyflavone have been reported previously, the observed (13)C chemical shifts were not assigned. A previously reported empirical predictive tool has been applied in reverse in order to deconvolute the (13)C chemical shifts for 8-hydroxyflavone from each of those of 7,8,4'-trihydroxyflavone and 7,8-dihydroxyflavone together with those of 7-hydroxyflavone, 4'-hydroxyflavone, and flavone. The two sets of calculated (13)C chemical shifts for 8-hydroxyflavone are in good agreement with each other in that the average absolute difference is 0.4 ppm. The previously reported but unassigned (13)C chemical shifts for 8-hydroxyflavone have been assigned by matching them with the averages of the two sets of calculated (13)C chemical shifts for 8-hydroxyflavone such that the minimum average absolute difference is 0.63 ppm. The assigned (13)C chemical shifts of 8-hydroxyflavone may be used, along with the (13)C chemical shifts of the remaining monohydroxyflavones, as part of a predictive tool to rapidly assess the (13)C NMR spectra of C8-hydroxylated flavonoids.

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What this paper is about

8-Hydroxyflavone is not found in nature. While the (13)C chemical shifts of 8-hydroxyflavone have been reported previously, the observed (13)C chemical shifts were not assigned. A previously reported empirical predictive tool has been applied in reverse in order to deconvolute the (13)C chemical shifts for 8-hydroxyflavone from each of those of 7,8,4'-trihydroxyflavone and 7,8-dihydroxyflavone together with those of 7-hydroxyflavone, 4'-hydroxyflavone, and flavone. The two sets of calculated (13)C chemical shifts for 8-hydroxyflavone are in good agreement with each other in that the average absolute difference is 0.4 ppm. The previously reported but unassigned (13)C chemical shifts for 8-hydroxyflavone have been assigned by matching them with the averages of the two sets of calculated (13)C chemical shifts for 8-hydroxyflavone such that the minimum average absolute difference is 0.63 ppm. The assigned (13)C chemical shifts of 8-hydroxyflavone may be used, along with the (13)C chemical shifts of the remaining monohydroxyflavones, as part of a predictive tool to rapidly assess the (13)C NMR spectra of C8-hydroxylated flavonoids.

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Available abstract

8-Hydroxyflavone is not found in nature. While the (13)C chemical shifts of 8-hydroxyflavone have been reported previously, the observed (13)C chemical shifts were not assigned. A previously reported empirical predictive tool has been applied in reverse in order to deconvolute the (13)C chemical shifts for 8-hydroxyflavone from each of those of 7,8,4'-trihydroxyflavone and 7,8-dihydroxyflavone together with those of 7-hydroxyflavone, 4'-hydroxyflavone, and flavone. The two sets of calculated (13)C chemical shifts for 8-hydroxyflavone are in good agreement with each other in that the average absolute difference is 0.4 ppm. The previously reported but unassigned (13)C chemical shifts for 8-hydroxyflavone have been assigned by matching them with the averages of the two sets of calculated (13)C chemical shifts for 8-hydroxyflavone such that the minimum average absolute difference is 0.63 ppm. The assigned (13)C chemical shifts of 8-hydroxyflavone may be used, along with the (13)C chemical shifts of the remaining monohydroxyflavones, as part of a predictive tool to rapidly assess the (13)C NMR spectra of C8-hydroxylated flavonoids.

Key concepts: Chemical shift, Chemistry, Chemical composition, Carbon-13 NMR, Analytical Chemistry (journal), Stereochemistry, Physical chemistry, Organic chemistry

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Empirically predicted 13C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone — Research Paper | ScholarLens