In a previous paper'it was shown that the flavonoid pigments of Coreopsis tinctoria consist of a chalcone, a flavanone and a benzalcoumaranone derivative of corresponding structure. It was found that the chalcone, marein, is oxidized easily to the corresponding aurone, maritimein, but at the same time it has a great tendency to isomerize into the related flavanone, flavanomarein. The unusual behavior shown by marein suggests that there ...
