Synthetic Applications. The ability to efficiently convert arenes into arynes is aptly suited to late-stage functionalization. We have demonstrated this concept on O-methyl triclosan 1x, the methylated derivative of an anti-bacterial agent found in many consumer products (Scheme 4a). In this case we subjected 1x to our standard one-pot conditions via the in situ generated aryl thianthrenium and the trapped aryne 3xa was isolated in 74% yield (Scheme 4a). We have also shown that aryne intermediates can be used to access several naphthalene derivatives, namely naphthoquinones, naphthalenes, and naphthols (Scheme 4b). Arene 1a was used as the starting material in all three cases. First, a one-pot method to transform 1a into the corresponding naphthoquinone is achieved in 66% yield when 2j is used in the aryne trapping step and the crude reaction mixture is stirred with trifluoroacetic acid (4; Scheme 4b). Second, the aryne adduct 3aa can be converted into a naphthalene via "oxygen deletion"; the two-pot process for generating naphthalene 5 from arene 1a proceeds in 43% overall yield (Scheme 4b). Finally, the oxabicyclic ring of 3aa can be ring opened with HCl to generate the functionalized 1-naphthol 6; this process can be conducted in a single-pot and 6 can be isolated in 60% overall yield from 1a (Figure ). Alternatively, 6 can be carried forward in the same flask to generate a derivative of propranolol (highlighted in grey on 7) in 34% overall yield from 1a (Figure ). Mechanistic Analysis. Our synthetic studies (vide supra) suggest that the two strategies described here for net arene dehydrogenation, one using aryl thianthrenium intermediates and the other using aryl(Mes)iodonium intermediates, have complementary arene scope. We have performed experiments to probe the mechanism of each step, C-H functionalization and aryne formation, and we have compared and contrasted the results for each strategy. We used deuterium kinetic isotope effects (DKIE), competition experiments, and Density Functional Theory (DFT), and our mechanistic analysis corroborates the suggestion of our synthetic studies; each step of the reaction has mechanistic subtleties that contribute to complementary overall scope based on the two aryl "onium" intermediates employed.