Structure reinvestigation of conyzorigun, a new chromone from Ageratum conyzoides

Abstract

A highly oxygenated chromone, conyzorigun (1), from Ageratum conyzoides plants was earlier reported to contain a novel stable ketene acetal system by virtue of an oxygen linkage between the benzopyrone and phenyl moieties. A reinvestigation of this structure in the light of biosynthetic experiments followed by chemical degradation is now described. The results obtained indicate that conyzorigun does not contain the above-described oxygen linkage, being a flavone of a known structure, viz. eupalestin (4).