Synthesis of Procyanidins C2 and C1 Using Lewis Acid Mediated Equimolar Condensation

Abstract

-Synthesis of procyanidin C2 and C1 was achieved via a stereoselective intermolecular condensation of equimolar amount of dimeric catechin or epicatechin nucleophile and monomeric catechin or epicatechin electrophile using Lewis acid. In the case of synthesis of procyanidin C2, AgBF 4 and AgOTf afforded condensed product in excellent yield. As to the synthesis of procyanidin C1, Yb(OTf) 3 was effective for equimolar condensation.

Isolation and characterization of a novel oligomeric proanthocyanidin with significant anti-cancer activities from grape stems (Vitis vinifera)

“…These compounds were analysed using ESI-TOFMS and NMR, and compared with the spectra of known compounds. Spectra of the dimeric to tetrameric units of epicatechin or catechin were obtained from synthesized materials 11,14,15 . Purification using Abmerlite XAD-1180N for the first stage with water followed by AcOEt, and MeOH as eluents afforded three fractions.…”