Oxidative coupling. Part VII. Biogenetic type synthesis of naturally occurring xanthones

Abstract

The co-occurrence of isomeric xanthones in certain plant extracts suggests their derivation from a common hydroxylated benzophenone. In vitro oxidation of some of these benzophenones produces xanthone mixtures corresponding to oxidative coupling occurring para and ortho or para only to an activating hydroxy-group. The oxidations can also be carried out enzymically.