Beilstein J. Org. Chem.2009,5, No. 60, doi:10.3762/bjoc.5.60
Medicine, Nanjing, Jiangsu 210046, P.R. China Division of Organic Chemistry, China Pharmaceutical University, Nanjing, Jiangsu 211198, China 10.3762/bjoc.5.60 Abstract An efficient partial 5-step synthesis of 4′-O-methylquercetin from quercetin in 63% yield is reported. This strategy relies on the
selective protection of the catechol group with dichlorodiphenylmethane in diphenyl ether as solvent and on the selective protection of the hydroxyl groups at positions 3 and 7 with chloromethyl ether.
Keywords: alkylation; high yield; 4′-O-methylquercetin; partial synthesis; regioselective protection
modifications of the phenolic hydroxyl groups: methylation, sulfation and glucuronidation [2]. Plasma analysis of pigs fed with quercetin-rich diets show that quercetin is absent and only methylated metabolites such as 4′-O-methylquercetin (2, tamarixetin) and 3′-O-methylquercetin (3, isorhamnetin, Figure 1
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Graphical Abstract
Figure 1:
Structures of quercetin and methylated metabolites.