Synthesis of high molecular mass condensed tannin by cationic polymerization of flavan 3,4-carbonate

Abstract

A new synthetic method for the preparation of high molecular mass (the highest M̄;n̄ 10 200) condensed tannin has been developed. Polymerization of 3′,4′,5,7-tetrabenzyloxyflavan 3,4-carbonate 2 and subsequent debenzylation gives a condensed tannin having high molecular mass. Molecular mass of the synthetic tannin increases up to a degree of polymerization (D̄P̄n̄) of ∼35 with an increase in the reaction time. This high molecular mass condensed tannin, synthesized for the first time, is useful as a model compound for natural condensed tannins with high molecular mass, such as that from Japanese persimmon (Diospyros kaki L.) fruit.

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