Molecules 2010, 15(7), 4722-4736; doi:10.3390/molecules15074722
Article

Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative

Andrea Mattarei 1 , Lucia Biasutto 2 , Federico Rastrelli 1 , Spiridione Garbisa 2 , Ester Marotta 1 , Mario Zoratti 2,3  and Cristina Paradisi 1,* email
1 Department of Chemical Sciences, Università di Padova, via Marzolo 1, 35131 Padova, Italy 2 Department of Biomedical Sciences, Università di Padova, viale G. Colombo 3, 35121 Padova, Italy 3 CNR Institute of Neuroscience, viale G. Colombo 3, 35121 Padova, Italy
* Author to whom correspondence should be addressed.
Received: 10 June 2010; in revised form: 22 June 2010 / Accepted: 2 July 2010 / Published: 6 July 2010
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Abstract: The regioselective synthesis of several quercetin (3,3’,4’,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.
Keywords: regioselective alkylation; mitochondrial targeting; quercetin; rhamnetin; polyphenols

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MDPI and ACS Style

Mattarei, A.; Biasutto, L.; Rastrelli, F.; Garbisa, S.; Marotta, E.; Zoratti, M.; Paradisi, C. Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative. Molecules 2010, 15, 4722-4736.

AMA Style

Mattarei A, Biasutto L, Rastrelli F, Garbisa S, Marotta E, Zoratti M, Paradisi C. Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative. Molecules. 2010; 15(7):4722-4736.

Chicago/Turabian Style

Mattarei, Andrea; Biasutto, Lucia; Rastrelli, Federico; Garbisa, Spiridione; Marotta, Ester; Zoratti, Mario; Paradisi, Cristina. 2010. "Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative." Molecules 15, no. 7: 4722-4736.

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