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.
MeSH terms
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Biflavonoids / chemical synthesis
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Biflavonoids / chemistry
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Borates / chemistry
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Catechin / analogs & derivatives
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Catechin / chemical synthesis
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Catechin / chemistry
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Dimerization
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Nuclear Magnetic Resonance, Biomolecular / methods
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Oxidation-Reduction
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Phenols / chemistry
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Proanthocyanidins / chemical synthesis*
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Proanthocyanidins / chemistry*
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Silver Compounds / chemistry
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Stereoisomerism
Substances
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3'-O-methylcatechin
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Biflavonoids
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Borates
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Phenols
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Proanthocyanidins
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Silver Compounds
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silver tetrafluoroborate
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procyanidin B
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Catechin