Carbonyl compounds Catechins

Our starting-point was the required definition of the bonding positions at either C-6 or C-8 of the presumed terminal (-h)-catechin [(2/ 3S)-2,3-rm .s-flavan-3,3, 4, 5,7-pentaol] unit which serves as initial nucleophile in most tannins under consideration. The solvent shift method for methoxyl function developed by Pelter et al (3), although applicable to the methyl ethers of biflavonoids (i. e. compounds with 3- or 4-carbonyl function), was less reliable when applied to the methyl ether acetates of biflavanoids, often leading to ambiguous or erroneous conclusions. ... 

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