Condensed tannins: A proposed route to 2R,3R-(2,3-cis)-proanthocyanidins

Abstract

Roux,¹ Haslam,^2-4 and Stafford^5-8 have proposed differing biogenetic schemes for the formation of proanthocyanidins (condensed tannins) in plants. All three schemes suffer from difficulties in explaining the formation of the 2R,3R-(2,3-cis)-proanthocyanidins that predominate in plant tannins. Stafford^5-8 has postulated that a C-3 epimerase acts on (+)-dihydroquercetin to provide the 2R,3S-(2,3-cis)-dihydroflavanol that would then be reduced to the corresponding 2R,3R,4S- (or 4R-) flavan-3,4-diol.

Citation

Hemingway, Richard W.; Laks, Peter E. 1985. Condensed tannins: A proposed route to 2R,3R-(2,3-cis)-proanthocyanidins. Journal of the Chemical Society Chemical Communications 746-747