Constitution of patuletin - Part II. A new synthesis of the flavonols of the quercetagetin series
L Ramachandra Row T R Seshadri
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A new and convenient synthesis of the flavonols of the quercetagetin series is described. ω: 4∶6-Trimethoxy-phloro-acetophenone has been prepared by two independent methods. By persulphate oxidation it is converted into the 2∶5-dihydroxy compound. Allan-Robinson condensation employing this ketone yields products containing a hydroxyl group in the 6-position. Subsequent demethylation and methylation yields the flavonols and their fully methylated ethers. Besides quercetagetin and tangeretin which occur in nature, 6-hydroxy galangin and 6-hydroxy myricetin which have not yet been discovered in natural products, have also been synthesised.
L Ramachandra Row1 T R Seshadri1