Structure and synthesis of phlobatannins related to bis-fisetinidol-epicatechin profisetinidin triflavanoids
1996
Bonnet, S.L. | Steynberg, J.P. | Bezuidenhoudt, B.C.B. | Saunders, C.M. | Ferreira, D.
The class of natural phlobatannins originating by stereoselective pyran rearrangement of the 2,3-trans-3,4-trans- and 3,4-cis-flavan-3-ol moieties in the hitherto unknown bis-fisetinidol-(4,6:4,8)-epicatechin profisetinidins is extended by identification of several novel analogues. These comprise four functionalized hexahydrodipyrano[2,3-f:2',3'-h]chromenes with an epicatechin DEF unit, as well as one based on an ent-catechin moiety, a fisetinidiol-(4 alpha,10)-tetrahydropyrano[2,3-f]chromene and a fisetinidol-(4 alpha,6)-tetrahydropyrano[2,3h]-chromene. The structure of one of the dipyranochromes was established unequivocally by synthesis via base-catalysed pyran ring rearrangement of the bis-fisetinidol-(4 alpha,6:4 alpha,8)-epicatechin triflavanoid.
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