Oxidative coupling of apigenin

Abstract Two novel biflavonyls have been prepared by phenolic oxidative coupling of apigenin, using alkaline potassium ferricyanide as the oxidizing agent. The structures of these dimers have been established as 3,3- and 3,3′-biapigeninyl respectively, primarily by spectroscopic methods. The synthetic compounds differ from all known natural biflavonyls in that linkage through the A ring of at least one of the flavonoid moieties is not observed. This indicates that the bioxynthesis of the natural compounds probably does not involve direct radical coupling.