Partial methylation of quercetin: Direct synthesis of tamarixetin, ombuin and ayanin



Methylalion of the penlahydroxy flavone, quercetin, was observed to proceed in distinct stages. From the reaction mixture (methyl sulfale/potassium carbonate/acetone), the isolation of three major intermediates, a mono-, a di- and a trimethyl ether and their identification as the naturally occurring ethers: tamarixelin, ombuin and ayanin is described.