848047-61-0

Upstream product

• 882867-42-7 Trifluoro-acetic acid (2R,3S)-5,7-bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-8-(2,2,2-trifluoro-acetyl)-chroman-3-yl ester 
• 882867-41-6 Trifluoro-acetic acid (2R,3S)-5,7-bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-chroman-3-yl ester 
• 100-44-7 benzyl chloride 
• 20728-73-8 5,7,3',4'-tetra-O-benzyl-(+)-catechin 
• 154-23-4 catechin 
• 100-39-0 benzyl bromide 
• 407-25-0 trifluoroacetic anhydride 

Relevant academic research and scientific papers

Influence of an 8-trifluoroacetyl group on flavanol couplings

The effect of an electron attracting substituent in the Lewis acid catalyzed oligomerization of flavanols was investigated. The results showed that the presence of a COCF3, at the 8 position of a (+)-catechin unit strongly influenced the attack of the 6 free nucleophile flavanol position by the electrophile generated from a 4-O-alkyloxy protected catechin unit. This was observed either with TiCl4 or TMSOTf as Lewis acids in which the carbon-carbon bond formation was inhibited and the corresponding dimer was detected in small amount. On the contrary, the formation of a carbon-oxygen bond was observed and the corresponding C-4→O→C-3 ether linked procyanidin dimer was isolated in a good yield. In order to avoid the participation of the C-3 hydroxyl group in the dimerization reaction, the two flavanol units were forced into C-4→C-8 coupling by use of an internal link. The structural elucidation of the isolated compounds was achieved through MS and NMR spectroscopy.

Hydroxylation of ring A of flavan-3-ols: Influence of the ring A substitution pattern on the oxidative rearrangement of 6-hydroxyflavan-3-ols

A general procedure for the oxidation of catechin derivatives is described, leading to the introduction of a new hydroxyl group at C-6. This procedure has been used for the synthesis of a number of 6-hydroxy flavan-3-ols, including elephantorrhizol, a natural flavan-3-ol exhibiting a fully substituted A ring. The substitution at C-8, albeit of poor influence on the course of this oxidation reaction, has been demonstrated to be preponderant for the further spontaneous oxidation and rearrangement of 6-hydroxy-flavan-3-ols into p-benzoquinones. The whole procedure allows the preparation of 6-alkyl substituted benzoquinones derived from catechin. Georg Thieme Verlag Stuttgart.

Synthesis of modified proanthocyanidins: Introduction of acyl substituents at C-8 of catechin. Selective synthesis of a C-4 → O → C-3 ether-linked procyanidin-like dimer

The regioselective introduction of substituents at C-8 of (+)-catechin is described, leading to the synthesis of several catechin derivatives with various substitution patterns to be used for the further synthesis of modified proanthocyanidins. Thereafter, a new 3-O-4 ether-linked procyanidin-like derivative was synthesized. Its formation was selectively achieved through TiCl4-catalyzed condensation of 4-(2-hydroxyethoxy)tetra-O-benzyl catechin with the 8-trifluoroacetyl adduct of tetra-O-benzyl catechin.