78139-46-5

Upstream product

• 490-46-0 (2R,3R)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1[2H]-benzopyran-3,5,7-triol 
• 51196-02-2 5,7,3',4'-tetra-O-methylepicatechin 
• 22970-70-3 (2R,3R,4S)-2,3-cis-3,4-trans-3',4',5,7-tetramethoxyflavan-3,4-diol 
• 108-24-7 acetic anhydride 
• 105561-65-7 octa-O-methylprocyanidin B-5 
• 105487-44-3 (2R,3S,4S,2'R,3'S)-2,2'-Bis-(3,4-dimethoxy-phenyl)-5,7,5',7'-tetramethoxy-3,4,3',4'-tetrahydro-2H,2'H-[4,6']bichromenyl-3,3'-diol 

Relevant academic research and scientific papers

SYNTHESIS AND CHARACTERIZATION OF PROCYANIDIN DIMERS AS THEIR PERACETATES AND OCTAMETHYL ETHER DIACETATES

Key Word Index - Biomimetic synthesis; procyanidins B1-B8; 3,4-cis-biflavanoid; all--bi--(+)-catechin; 1H NMR parameters. Condensation of (2R,3S,4R or S)-leucocyanidin or the 5,7,3',4'-tetramethyl ether of (2R,3R,4S)-leucocyanidin with flavan-3-ols yielded dimeric flavanoids which were converted to their octamethyl ether diacetates, or the deca-acetates for the 2,3-trans-procyanidin series.Comparison is made of the 1H NMR spectra of the deca-acetate and octamethyl ether diacetate derivatives which lead to useful diagnostic shift parameters characteristic of their structures.Condensation afforded a novel biflavanoid with a 3,4-cis-configuration and a triflavanoid of 'mixed' stereochemistry.

Synthesis of Condensed Tannins. Part 12. Direct Access to - and -all-2,3-cis-Procyanidin Derivatives from (-)-Epicatechin: Assessment of Bonding Positions in Oligomeric Analogues from Crataegus oxyacantha L.

Synthesis of methyl ester acetates of - and -all-2,3-cis-procyanidin biflavanoids is effected by oxidative functionalization of (-)-epicatechin tetramethyl ester with lead tetra-acetate, and condensation of the resultant 2,3-cis-flavan-3,4-diol

Synthesis of Condensed Tannins. Part 9. The Condensation Sequence of Leucocyanidin with (+)-Catechin and with the Resultant Procyanidins

Molar equivalents of synthetic (2R,3S,4R of S)-leucocyanidin and (+)-catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-- and -bi- (procyanidins B3, B6) the all-trans-- and -tri- (procyanidin C2, and novel isomer), and the presumed all-trans--linked tetraflavanoid analogue in the proportions 10:1:12:1:3.The facility and sequence of these condensations correlate with the observed absence of leucocyanidins (flavan-3,3',4,4',5,7-hexaols) and also the dominance of related condensed tannins in plant extracts.

Synthesis of Condensed Tannins. Part 4. A Direct Biomimetic Approach to - and -Biflavanoids

The generation of flavanyl-4-carbo-cations from flavan-3,4-diols and their condensation with nucleophilic flavan-3-ols to form - and -biflavanoids at ambient temperatures and mildly acidic aqueous conditions apparently simulates the initial step in condensed tannin formation in a number of natural sources.The stereospecificity (or stereoselectivity) of the reaction is conditioned mainly by the 2,3-cis or 2,3-trans stereochemistry of the parent flavan-3,4-diol, but also by the nuclephilicity of the flavan-3-ol, and its regiospecific (or regioselective) course by steric factors arising from variation in substitution of the receptive A-ring of the flavan-3-ol.