%0 Journal Article
%T Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative
%A Andrea Mattarei
%A Lucia Biasutto
%A Federico Rastrelli
%A Spiridione Garbisa
%A Ester Marotta
%A Mario Zoratti
%A Cristina Paradisi
%J Molecules
%D 2010
%I MDPI AG
%R 10.3390/molecules15074722
%X The regioselective synthesis of several quercetin (3,3กฏ,4กฏ,5,7-pentahydroxy flavone) tetraesters bearing a single free OH on 5-C was achieved in good yield by proper choice of reaction conditions using common esterification procedures. Tetracetylated quercetin with the free OH on 7-C was selectively obtained instead via imidazole-promoted deacylation of the corresponding pentaester. Unambiguous structural characterization of the two isomeric tetraacetyl quercetin derivatives was obtained by combined HSQC and HMBC 2D-NMR analysis. These molecules can be used as starting materials for the regioselective synthesis of other derivatives. High yield syntheses of the natural polyphenol rhamnetin (7-O-methylquercetin) and of the new mitochondriotropic compound 7-(4-triphenylphosphoniumbutyl) quercetin iodide are reported as examples.
%K regioselective alkylation
%K mitochondrial targeting
%K quercetin
%K rhamnetin
%K polyphenols
%U http://www.mdpi.com/1420-3049/15/7/4722