A new structure is proposed, on the basis of spectroscopic and chemical evidence, for the yellow compound diethyl xanthophanic enol formed when ethyl sodioacetoacetate and ethyl ethoxymethyleneacetoacetate are heated together. A mechanism of formation is outlined and supported. The new information is used to prepare various compounds of the xanthyrone class and two of these, 3, 3′, 3′, 5-tetra-acetyl-6-propenyl-α-pyrone and 3′ ...
