DEMETHYLATION-SULFONATION OF 2',3',4'-TRIMETHOXYFLAVONES

摘要

Total demethylation of 2',3',4'-trimethoxyflavones with sulfuic acid was realised at mild temperature giving respective 2',3',4'-trihydroxyflavone-5'-sulfonic acids. A multi steps mechanism is proposed in the light of earlier results and the complete assignment of the ~1H and ~(13)C NMR spectra of a suggested 3'-hydroxy-2',4'-dimethoxy intermediate.