Oxidation of unsymmetrically sunstituted 1,3-diarylpropynones in a system trifluoroacetic acid-dichloromethane-lead(IV) oxide proceeds through intermediate formation of cation radicals and occurs regio- and stereoselectively affording E-1,1,2,2-tetraaroylethenes. The highest yield of these compounds was obtained from 1,3-diarylpropynones containing electron-donor methoxy and methyl groups in the aromatic ring conjugated with the triple bond.