294203-73-9

Upstream product

• 18162-48-6 tert-butyldimethylsilyl chloride 
• 20728-73-8 5,7,3',4'-tetra-O-benzyl-(+)-catechin 
• 294203-71-7 [(2R,3S)-5,7-Bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-chroman-3-yloxy]-tert-butyl-dimethyl-silane 

Downstream Products

• 1030624-95-3 C₅₁H₅₄O₈Si 
• 137624-11-4 (2R,3S,4S)-5,7-Bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-chroman-3,4-diol 
• 294203-74-0 (2R,3R)-5,7-Bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-3-(tert-butyl-dimethyl-silanyloxy)-chroman-4-one 

Relevant academic research and scientific papers

Cationic zirconocene- or hafnocene-based Lewis acids in organic synthesis: Glycoside-flavonoid analogy

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.

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

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.

First synthesis of astilbin, biologically active glycosyl flavonoid isolated from Chinese folk medicine

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.