Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The structure VIb, suggested previously on the basis of physico-chemical data for the compound reported to be the sole product of thermolysis of 2,6-ditert-butyl-4-diazo-2,5-cyclohexadien-1-one (IV) in the presence of diphenylacetylene, is incorrect. We have now shown that the main product is in fact 4-(3',5'-ditert-butyl-4'-hydroxybiphenyl)phenylacetylene (VIII). Other, minor, products of this reaction are the isomeric ketones VIIb and IX, the diphenoquinone XI and the cyclic azo compound XII. A small quantity of the spirotrienone VIb was isolated only when the reaction had been performed with a large excess of diphenylacetylene. The structure of VIb was determined unequivocally by physico-chemical methods and chemical transformations to compounds, prepared by independent syntheses. Air-oxidation of the ketone VIIb in an alkaline medium afforded the quinone methide X.