The isoelectronic series lead tetraacetate–hydrogen fluoride, lead tetraacetate, thallium(III) acetate, and mercuric acetate were used to oxidize the bicyclic olefin dibenzobicyclo[2.2.2]octatriene. The stereochemistry of the products formed from these reactions substantiates the proposal that the first formed intermediate in these oxidations is thecis-molecular addition product of the metal and its ligand to the bicyclic olefin. Subsequent stereospecific rearrangement of the adducts in the case of the lead and thallium reagents verified the absence of the involvement of homolytic processes in the formation or decomposition of the adducts.