| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5270714 | Tetrahedron Letters | 2014 | 6 Pages |
Abstract
Bromination of quercetin with N-bromosuccinimide in neutral aqueous methanol occurs surprisingly in the electron-deficient A-ring only. Deprotonation of the acidic 7-OH is a major driver of this regioselective reaction. The increase of electron density makes in fact the quercetin anion suitable for an electrophilic attack by bromine at positions 8 and 6. Several pieces of evidence (NMR spectra and H/D exchange) are presented to substantiate the mechanism advanced. Bromoquinones/quinomethides produced in excess of N-bromosuccinimide are responsible for the formation of a stable 'violet chromogen'.
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Related Topics
Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Mario C. Foti, Concetta Rocco,