223387-51-7Relevant articles and documents
Synthesis of modified proanthocyanidins: Introduction of acyl substituents at C-8 of catechin. Selective synthesis of a C-4 → O → C-3 ether-linked procyanidin-like dimer
Beauhaire, Josiane,Es-Safi, Nour-Eddine,Boyer, Francois-Didier,Kerhoas, Lucien,Le Guerneve, Christine,Ducrot, Paul-Henri
, p. 559 - 562 (2005)
The regioselective introduction of substituents at C-8 of (+)-catechin is described, leading to the synthesis of several catechin derivatives with various substitution patterns to be used for the further synthesis of modified proanthocyanidins. Thereafter, a new 3-O-4 ether-linked procyanidin-like derivative was synthesized. Its formation was selectively achieved through TiCl4-catalyzed condensation of 4-(2-hydroxyethoxy)tetra-O-benzyl catechin with the 8-trifluoroacetyl adduct of tetra-O-benzyl catechin.
An improved synthesis of procyanidin dimers: Regio- and stereocontrol of the interflavan bond
Tarascou, Isabelle,Barathieu, Karine,Andre, Yann,Pianet, Isabelle,Dufourc, Erick J.,Fouquet, Eric
, p. 5367 - 5377 (2007/10/03)
A direct and general synthesis of procyanidin dimers B1, B2, B3 and B4 (10a-d) is presented. The approach is based on the stoichiometric coupling of two protected monomeric units (the nucleophilic 2a-b and electrophilic 4a-b partners) and deals with the regio- and stereocontrol of the C4-C8 interflavan bond as well as the control of the degree of oligomerization. The synthesis involves a five-step pathway starting from the native catechin (1a) or epicatechin (1b) to the fully deprotected dimers 10a-d. Furthermore, the process appears to be iterative as the coupling intermediates 9a-d themselves can be readily used in further selective syntheses of trimers or higher oligomers. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Synthetic studies of proanthocyanidins. Part 2: Stereoselective gram-scale synthesis of procyanidin-B3
Saito, Akiko,Nakajima, Noriyuki,Tanaka, Akira,Ubukata, Makoto
, p. 7829 - 7837 (2007/10/03)
A stereoselective synthesis of procyanidin-B3, a condensed catechin dimer, is described. Condensation of benzylated catechin with various 4-O-alkylated flavan-3,4-diol derivatives as an electrophile in the presence of a Lewis acid led to protected procyanidin-B3 and its diastereomer. In particular, the reaction using (2R,3S,4S)-3-acetoxy-5,7,3′,4′-tetrabenzyloxy-4-(2″- ethoxyethoxy)flavan as an electrophile in the presence of TMSOTf at -78°C afforded octa-O-benzylated procyanidin-B3 with high levels of stereoselectivity and in excellent isolation yields. Furthermore, we succeeded in a stereoselective gram-scale synthesis of protected procyanidin-B3.
