Condensed tannins. 7. Isolation of (−)-7:3′:4′-trihydroxyflavan-3-ol [(−)-fisetinidol], a naturally occurring catechin from black-wattle heartwood

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Abstract
(-)-7:3'':4''-Tri-hydroxyflavan-3-ol [(-)-fiset-inidol], a new catechin, has been isolated from the heartwood of Acacia mollissima. The radial distribution of the substance in the wood has been estimated. (-)-Fisetinidol has also been prepared synthetically by the hydrogenation of (+)-7:3'':4''-trihydroxyflavan-3;4-diol. The new catechin has the same configuration at C-2 and C-3 as (+)-7:3'':4''-trihydroxyflavan-3;4 diol and as (+)-fustin, all of which occur in the wood. The suggestion is made that the flavan -3 ;4 -diol is the single precursor from which the corresponding catechin, 2;3-dihydro-flavonol and flavonol arise by interconversion, and the accompanying leuco-fisetinidin condensed tannins by condensation.