[EN] METHOD FOR THE PREPARATION OF C-4 COUPLED FLAVONOIDS, PROANTHOCYANIDINS AND ANALOGUES THEREOF [FR] PROCÉDÉ DE PRÉPARATION DE FLAVONOÏDES COUPLÉS EN C-4, DE PROANTHOCYANIDINES ET D'ANALOGUES CORRESPONDANTS
Synthesis of Proanthocyanidins. Part 1. The First Oxidative Formation of the Interflavanyl Bond in Procyanidins
作者:Matthew C. Achilonu、Susan L. Bonnet、Jan H. van der Westhuizen
DOI:10.1021/ol801353u
日期:2008.9.1
A novel and efficient method for the oxidative condensation of tetra-O-methyl-3-oxocatech in 4 with tetra-O-methylcatechin is described. Treatment of a solution of 3 (2 equiv) and 4 (1 equiv) with silver tetrafluoroborate readily affords the phenolic per-O-methyl ethers of 3-oxocatechin(4-8)-catechin 18 and 19. Subsequent metal hydride reduction provides access to procyanidin B-3 analogues with the 3,4-cis diastereomers predominating.