Contrary to previous reports cyclohexanone and pinacolone are not oxidized to the corresponding Baeyer–Villiger oxidation products during ozonolysis of ethylidenecyclohexane in their presence. Addition of propionaldehyde to a solution of the 1,2,3-trioxolane initial ozonide of trans-1,2-di-t-butylethylene resulted in oxidation of the aldehyde to propionic acid and reduction of the 1,2,3-trioxolane to pivaldehyde. Thus, there is no necessity for the four-membered Staudinger molozonide as an ozonolysis intermediate, as recently proposed by Story.