22970-70-3Relevant articles and documents
REGIO- AND STEREOSELECTIVE OXYGENATION OF FLAVAN-3-OL-, 4-ARYLFLAVAN-3-OL-, AND BIFLAVANOID-DERIVATIVES WITH POTASSIUM PERSULPHATE
Mouton, C. Hendrik L.,Steenkamp, Jacobus A.,Young, Desmond A.,Bezuidenhoudt, Barend C. B.,Ferreira, Daneel
, p. 6885 - 6894 (2007/10/02)
The phenolic methyl ethers of flavan-3-ols, 4-arylflavan-3-ols, and (-)-fisetinidol-(4,8)-(+)-catechin biflavanoids are susceptible to regio- and stereoselective hydroxylation at C-4 in moderate to high yields with potassium persulphate/cupric sulphate in aqueous acetonitrile.The resultant 4-functionalized analogues are of both synthetic and degradative significance in condensed tannin chemistry.
Heterocycles. XXV. Sodium Borohydride Reduction of Flavanonols
Li, Shaoshun,Onda, Masayuki,Kagawa, Hitoshi,Kawase, Hiromi,Iguchi, Mieko,Harigaya, Yoshihiro
, p. 2029 - 2035 (2007/10/02)
Solvent effects on the stereochemistry in the sodium borohydride reduction of (+/-)-flavanonols have been examined.The effects observed for the (+/-)-flavanonols with 5-OMe in 2-propanol, dioxane and methanol are explainable by the differences between the steric interactions inherent in the product-like transition states A and B.It has been also found that 5-OAc peculiarly affects the stereochemistry in the reduction to produce the (+/-)-catechin-type compounds in a one-pot process.The solvent and temperature effects are examined using a model analogous to the above.
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.
Kolodziej, Herbert,Ferreira, Daneel,Roux, David G.
, p. 343 - 350 (2007/10/02)
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
OCCURRENCE OF PROCYANIDINS IN NELIA MEYERI
Kolodziej, Herbert
, p. 1745 - 1752 (2007/10/02)
A novel natural 4-arylflavan-3-ol has been obtained from leaves of Nelia meyeri.The same extract contains two procyanidin dimers, B-2 and B-5, and trimer C-1. 1H NMR studies furnish diagnostic chemical shift parameters for determining the points of linkag
HETEROCYCLES. XIV. EFFICIENT STEREOCONTROLLED SYNTHESIS OF RACEMIC FLAVONOIDS
Takahashi, Hiroshi,Kubota, Yumiko,Miyazaki, Hiroko,Onda, Masayuki
, p. 1147 - 1153 (2007/10/02)
Stereocontrolled synthesis of the flavonoids (2, 4 and 5) is described.Racemic taxifolin (dihydroquercetin) (14) is synthesized by application of this method.
THE FIRST NATURALLY OCCURRING 4-ARYL FLAVAN-3-OL
Kolodziej, Herbert
, p. 1825 - 1828 (2007/10/02)
(2R,3R,4S)-4-(2,4,6-trihydroxyphenyl)flavan-3,3',4',5,7-pentaol, the first natural 4-aryl flavan-3-ol, was isolated from Nelia meyeri Schwant., and its structure and stereochemistry determined by spectroscopic investigation and synthesis.
LEUCOCYANIDIN: SYNTHESIS AND PROPERTIES OF (2R,3S,4R)-(+)-3,4,5,7,3',4'-HEXAHYDROXYFLAVAN
Porter, Lawrence J.,Foo, L. Yeap
, p. 2947 - 2952 (2007/10/02)
An isomer of leucocyanidin, (2R,3S,4R)-(+)-3,4,5,7,3',4'-hexahydroxyflavan has been synthesized from (+)-taxifolin, isolated in its phenolic form, and characterized by 1H and 13C NMR, and formation of the 5,7,3',4'-tetramethyl ether.Leucocyanidin readily polymerizes in acid solution to form a procyanidin polymer of high MW. - Key Word Index: Leucocyanidin; flavan-3,4-diols; synthesis; polymerization; phytochemical significance.
