137624-12-5

Upstream product

• 1217257-69-6 3’,4’,5,7-tetra-O-benzyl-4β-O-propargylcatechin 
• 20728-73-8 5,7,3',4'-tetra-O-benzyl-(+)-catechin 
• 596829-27-5 C₉₀H₇₆O₁₄ 
• 137624-11-4 (2R,3S,4S)-5,7-Bis-benzyloxy-2-(3,4-bis-benzyloxy-phenyl)-chroman-3,4-diol 
• 664351-41-1 (2R,3S,4S)-3-acetoxy-5,7,3',4'-tetrabenzyloxy-4-(2-ethoxyethoxy)flavan 
• 294203-72-8 (2R,3S,4S)-5,7,3',4'-tetrabenzyloxy-4-methoxyflavan-3-ol 

Downstream Products

• 51196-37-3 3,4-cis-(+)-catechin-(4β->8)-(+)-catechin 

Relevant academic research and scientific papers

Procyanidin B3 synthesis: a study of leaving group and Lewis acid activator effects upon interflavan bond formation

A range of electrophilic ethers were prepared via DDQ oxidation and alcoholic trapping (propanol, crotyl alcohol and propargyl alcohol) at the C4 position of (+)-catechin. The Lewis acid-mediated C4-substitution of each of these ethers was examined and it was found that the propargyl ether was the best overall electrophile. A range of Lewis acids were then examined as activators and it was found that BF3·OEt2 was the best in terms of both yield and stereochemical control at the C4 position. This newly developed set of conditions was then used to prepare the natural product nutraceutical procyanidin B3 with complete control of stereochemistry.

Synthetic studies of proanthocyanidins. Part 3: Stereoselective 3,4-cis catechin and catechin condensation by TMSOTf-catalyzed intramolecular coupling method

TMSOTf-catalyzed intramolecular condensation for catechin and epicatechin units are described. A potential electrophile and a nucleophile were connected with diester linkers and TMSOTf-catalyzed condensation was examined. In comparison with intermolecular

Synthetic studies of proanthocyanidins. Highly stereoselective synthesis of the catechin dimer, procyanidin-B3.

A stereoselective synthesis of benzylated procyanidin-B3, a condensed catechin dimer, is described. Condensation of 5,7,3',4'-tetrabenzylcatechin with (2R,3S,4S)-5,7,3',4'-tetrabenzyloxy-3-acetoxy-4-methoxyflavan as an electrophile in the presence of TiCl4 led to octabenzylated procyanidin-B3 stereoselectively.

Synthetic studies of proanthocyanidins. Part 2: Stereoselective gram-scale synthesis of procyanidin-B3

A stereoselective synthesis of procyanidin-B3, a condensed catechin dimer, is described. Condensation of benzylated catechin with various 4-O-alkylated flavan-3,4-diol derivatives as an electrophile in the presence of a Lewis acid led to protected procyanidin-B3 and its diastereomer. In particular, the reaction using (2R,3S,4S)-3-acetoxy-5,7,3′,4′-tetrabenzyloxy-4-(2″- ethoxyethoxy)flavan as an electrophile in the presence of TMSOTf at -78°C afforded octa-O-benzylated procyanidin-B3 with high levels of stereoselectivity and in excellent isolation yields. Furthermore, we succeeded in a stereoselective gram-scale synthesis of protected procyanidin-B3.

Deuterium labeled procyanidin syntheses

Deuterium-labeled procyanidins have been prepared by hemisynthesis from taxifolin in order to investigate their metabolism in human. The structures of the desired deuterated natural compounds B3 10D (R1 = D, R2 = H) and B4 13D (R1 = D, R2 = H) were proven by spectroscopic and physical properties means, including 2H NMR spectrum. By-products with unatural absolute configuration at some centers were also formed along the process and were characterised.