Given that the oxidation of the bicyclobutane framework constitutes an activation mode that has been underexplored in synthesis, trapping studies and radical clock experiments were next conducted to probe their effect on the reaction outcome. Surprisingly, when radical trapping agent TEMPO was added to the standard reaction, product formation was not entirely suppressed, whereas the addition of MeOH resulted in only trace product being observed (Fig. ). In the case of TEMPO, the observation of a 1:1:1 trapping adduct (assigned as structure 6), suggests that a carbon-centred radical is localised at the C8 position. To confirm the presence of this intermediate, cyclopropane-containing alkenes 2z and 4ay were subjected to standard reaction conditions. However, no cyclopropane ring opening could be detected in either case and cycloadducts 3z and 5ay were isolated in 40% and 41% yield, respectively (Fig. ). From these apparently contradictory results it was unclear whether the initial interaction of the BCB radical cation and the alkene proceeds via radical addition to give an intermediate of type 8, or occurs via alkene nucleophilic addition (9, Fig. ). Therefore, we turned to computational calculations to provide key insights into the operative mechanism.