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A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)
Dipartimento di Agrobiologia e Agrochimica, Università degli Studi della Tuscia, Via S. Camillo De Lellis, 01100 Viterbo, Italy
* Author to whom correspondence should be addressed.
Received: 16 November 2010; in revised form: 23 January 2011 / Accepted: 27 January 2011 / Published: 9 February 2011
Abstract: Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated flavonoids exhibited a superior anticancer activity than the corresponding hydroxylated derivatives being more resistant to the hepatic metabolism and showing a higher intestinal absorption. In this communication we describe a convenient and efficient procedure in order to prepare a large panel of mono- and dimethylated flavonoids by using dimethyl carbonate (DMC), an ecofriendly and non toxic chemical, which plays the role of both solvent and reagent. In order to promote the methylation reaction under mild and practical conditions, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added in the solution; methylated flavonoids were isolated in high yields and with a high degree of purity. This methylation protocol avoids the use of hazardous and high toxic reagents (diazomethane, dimethyl sulfate, methyl iodide).
Keywords: methylated flavonoids; ecofriendly methylation reaction; dimethyl carbonate (DMC); green chemistry
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Bernini, R.; Crisante, F.; Ginnasi, M.C. A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC). Molecules 2011, 16, 1418-1425.
Bernini R, Crisante F, Ginnasi MC. A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC). Molecules. 2011; 16(2):1418-1425.
Bernini, Roberta; Crisante, Fernanda; Ginnasi, Maria Cristina. 2011. "A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)." Molecules 16, no. 2: 1418-1425.