To assess the stability of the tertiary alcohol under the reaction conditions, we exposed 1-adamantanol (11d) to dual Brønsted/Lewis acid catalysis conditions (Scheme 7a). In the absence of the arene substrate, 1-bromoadamantane (15) was isolated in 28% yield. Subjecting the same reaction to 1 equivalent of FeBr3 increased the yield to 87%. To probe whether the reaction proceeds through a closed-or open-shell pathway, we investigated the capturing of putative radical intermediates using various Michael acceptors 17 (Scheme 7b). The potential for a 1-electron reduction of the newly formed carbon-halogen bond using an iron (II) catalyst was examined. However, attempts to generate radical species from both 1adamantanol (11d) and 1-bromoadamantane (15) were deemed unsuccessful because we were unable to observe any alkyl addition to the Michael acceptors. Initially, methyl acrylate and phenyl acrylate were tested, however both proved ineffective, as did others that were investigated (see SI). If a radical intermediate forms from alkenol 18, the resulting tertiary radical could cyclize onto the alkene but attempts to react it with 2-methylanisole (1o) resulted in a mixture of products with no indication of cyclization to cyclopentyl 19. Addition of substoichiometric TEMPO reduced reactivity to 12% conversion and stoichiometric TEMPO halted reactivity. However, in the absence of other compelling data, we interpret this as a competitive interaction between TEMPO and the iron reagent that leads to catalyst arrest. This is supported by the lack of TEMPO-adducts observed, which are otherwise expected to form from the quenching of arene radical or tertiary alkyl radical species. While less common than TEMPO, nitroso compounds exert radical scavenging properties. As such, we rationalized that 2-nitroso-1-naphthol (20) could potentially differentiate radical and polar pathways. The donating capacity of the phenolic group could render the nitroso functionality reactive towards polar electrophiles to give oxime ether 21. Alternatively, radical intermediates would engage the nitroso group to arrive at hydroxylamine 22. Under the reaction conditions, only oxime ether 21 was formed in 18% yield with the remainder of the mass balance attributed to unreacted starting materials. Amine 22 was not detected in the reaction mixture. In addition, we employed density functional theory (DFT) calculations with energies refined at the B2PLYP-D3/def2-TZVPPD level of to assess the thermodynamics of closed-and open-shell pathways for activation of t-BuOH by FeCl3 through a polar pathway or FeCl2 through a radical pathway using equations 1 (ΔG°/ΔH° = 15.8/18.2 kcal•mol -1 ) and 2 (ΔG°/ΔH° = 42.5/46.7 kcal•mol -1 ), respectively: