294203-71-7Relevant academic research and scientific papers
First synthesis of astilbin, biologically active glycosyl flavonoid isolated from Chinese folk medicine
Ohmori, Ken,Ohrui, Hiroki,Suzuki, Keisuke
, p. 5537 - 5541 (2000)
A synthetic route to a biologically active glycosyl flavonoid, astilbin (1), was developed. The tetra-benzyl ether 4, derived from (+)-catechin, was glycosylated with the L-rhamnosyl donor 10 by using Cp2HfCl2-AgClO4, and subsequent oxidation of the C(4)position of the flavan skeleton followed by deprotection gave 1. (C) 2000 Elsevier Science Ltd.
Synthesis of procyanidins by stepwise- and self-condensation using 3,4-cis-4-acetoxy-3-O-acetyl-4-dehydro-5,7,3′,4′-tetra-O-ben zyl-(+)-catechin and (-)-epicatechin as a key building monomer
Oyama, Kin-ichi,Kuwano, Miyuki,Ito, Mie,Yoshida, Kumi,Kondo, Tadao
, p. 3176 - 3180 (2008/09/20)
3,4-cis-4-Acetoxy-3-O-acetyl-4-dehydro-5,7,3′,4′-tetra-O-ben zyl-(+)-catechin (1a) or (-)-epicatechin (1b) reacted high regio- and stereo-selectively with 1.5 equiv of the 5,7,3′,4′-tetra-O-benzyloxyflavan-3-ol (4a or 4b) in the presence of 1 equiv of TMSOTf to give the corresponding procyanidins. On the other hand, the self-condensation of 1a in the presence of a catalytic amount of B(C6F5)3 afforded wide-range procyanidins from dimer to 15-mer like a biomass.
Cationic zirconocene- or hafnocene-based Lewis acids in organic synthesis: Glycoside-flavonoid analogy
Ohmori, Ken,Hatakeyama, Keisuke,Ohrui, Hiroki,Suzuki, Keisuke
, p. 1365 - 1373 (2007/10/03)
Cationic metallocene species, generated from Cp2MCl2 and AgClO4 (M=Zr, Hf), were used for the glycosylation of catechin derivative 2, enabling a concise synthesis of a glycosyl flavonoid, astilbin (1). Further study revealed the efficiency of this Lewis acidic species for SN1-type activation of the C(4) position of catechin derivative 11, enabling selective substitution with various nucleophiles.
