title: Synthesis of proanthocyanidins. Part 1. The first oxidative formation of the interflavanyl bond in procyanidins.
abstract: A novel and efficient method for the oxidative condensation of tetra-O-methyl-3-oxocatechin 4 with tetra-O-methylcatechin is described. Treatment of a solution of 3 (2 equiv) and 4 (1 equiv) with silver tetrafluoroborate readily affords the phenolic per-O-methyl ethers of 3-oxocatechin(4-8)-catechin 18 and 19. Subsequent metal hydride reduction provides access to procyanidin B-3 analogues with the 3,4-cis diastereomers predominating.
authors.affiliation: Department of Chemistry, University of the Free State, Nelson Mandela Avenue, Bloemfontein, 9301, South Africa.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Achilonu
authors.forename: Susan L
authors.initials: SL
authors.lastname: Bonnet
authors.forename: Jan H
authors.initials: JH
authors.lastname: van der Westhuizen
mesh_terms: D044946:Biflavonoids / Q000138:chemical synthesis / Q000737:chemistry; D001881:Borates / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry; D019281:Dimerization; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry; D044945:Proanthocyanidins / Q000138:chemical synthesis* / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C480347:3'-O-methylcatechin; D044946:Biflavonoids; D001881:Borates; D010636:Phenols; D044945:Proanthocyanidins; D018030:Silver Compounds; C064097:silver tetrafluoroborate; C479578:procyanidin B; D002392:Catechin