Structure and synthesis of phlobatannins related to the (4α,6:4β,8)- bis-fisetinidol-catechin profisetinidin triflavanoid

Article abstract of DOI:10.1016/0031-9422(96)00239-7

The natural class of phlobaphene condensed tannins is complemented by two functionalized hexahydrodipyrano[2,3-f:2',3'-h]chromenes representing the products of stereoselective pyran ring rearrangement of the 2,3-trans-3,4- trans- and 2,3-trans-3,4-cis-flavan-3-ol moieties in the bis-fisetinidol- (4α,6:4β,8)-catechin triflavanoid. Structural elucidation of these complex natural products was effected by synthesis via base catalysed conversion of the 4-O(E)-methyl ether of their presumed protisetinidin triflavanoid precursor.