- 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
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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.
- Beauhaire, Josiane,Es-Safi, Nour-Eddine,Boyer, Francois-Didier,Kerhoas, Lucien,Le Guerneve, Christine,Ducrot, Paul-Henri
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- From the gold-catalysed benzylation of arenes to the regio- and stereoselective synthesis of procyanidins dimers
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This work reports on a new intermolecular C-C coupling reaction between electron rich arenes and benzylic alcohols or ethers, catalysed by gold(III) salts, or other catalysts such as gold(I) and iron (III), and its application to the regio- and stereoselective synthesis of procyanidins dimers B1 and B3.
- Fabre, Sandy,Gueroux, Marie,Nunes, Emeline,Szlosek-Pinaud, Magali,Pianet, Isabelle,Fouquet, Eric
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p. 3045 - 3051
(2015/05/04)
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- An improved synthesis of procyanidin dimers: Regio- and stereocontrol of the interflavan bond
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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.
- Tarascou, Isabelle,Barathieu, Karine,Andre, Yann,Pianet, Isabelle,Dufourc, Erick J.,Fouquet, Eric
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p. 5367 - 5377
(2007/10/03)
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- Compositions and methods of use of dimer digallates
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The invention relates to compositions, such as pharmaceuticals, foods, food additives, or dietary supplements, containing dimer digallates, and methods of use thereof, for prophylactic or therapeutic treatment of a human or a veterinary animal to treat or prevent NO-responsive health conditions, treat hypertension, cardiovascular disease, coronary artery disease, diabetes, cognitive dysfunction or disorder and/or vascular circulation disorders, prevent or reduce the risk of heart attack, stroke, congestive heart failure and/or kidney failure, or to improve blood flow, for example renal blood flow. The composition may optionally contain an additional NO modulating agent and/or a vascular-protective or therapeutic agent, or may be administered in combination with such an agent.
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Page/Page column 13
(2010/02/15)
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- Synthetic studies of proanthocyanidins. Part 2: Stereoselective gram-scale synthesis of procyanidin-B3
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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.
- Saito, Akiko,Nakajima, Noriyuki,Tanaka, Akira,Ubukata, Makoto
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p. 7829 - 7837
(2007/10/03)
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