During evaluation of the scope of the one-pot method we found that several feedstock arenes resulted in low yield (Figure ). Specifically, when we attempted to use benzene, toluene, anisole, or 1,3-dimethoxybenzene in this reaction we only observed trace (< 5%) yield of trapped aryne product (Figure ). However, C-H thianthrenation of these arenes is well-established; moreover, we have independently synthesized the corresponding aryl thianthrenium salts and observed trace yield when we attempted to generate and trap the corresponding arynes. Increased scope. In order to address the observed gaps in the scope of arenes for the one-pot net dehydrogenation via aryl thianthrenium intermediates, we considered alternative "onium" leaving groups. Our prior work in the area of generating arynes from aryl "onium" reagents suggested that iodonium leaving groups might be a viable intermediate to dovetail these missing arenes and their corresponding arynes. Although, several aryliodonium leaving groups are known in the context of generating arynes, including phenyl, mesityl, 8,14-17,22 and 2,4,6trimethoxyphenyliodonium, we hypothesized that the mesityliodonium is uniquely suited to this role for two key reasons. First, the 2,6-dimethyl groups of mesityl block deprotonation on the mesityl ring and lead to selective aryne formation on the other ring of the diaryliodonium salts; this scenario is not necessarily predictable with the phenyliodonium leaving group. Second, the mesityliodonium group may be installed by C-H functionalization of arenes using commercially available mesityliodine diacetate; this scenario is not generally possible for installation of the 2,4,6-trimethoxyphenyliodonium group. We modified Dohi and Kita's conditions to synthesize and isolate aryl(Mes)iodonium salts and then used these as reagents to generate arynes and trap them with furan; in all cases the reported yields are for the two-step procedure from the simple arene (Scheme 3). We were unable to develop a one-pot procedure, as in the case of aryl thianthrenium intermediates, because we found that both the synthesis of and use of diaryliodoniums as aryne precursors is substantially more sensitive to solvent effects and low yields were observed in acetonitrile as the sole solvent. In the case of benzene we used commercially available phenyliodine diacetate (PIDA) because, consistent with Dohi and Kita's prior observations, benzene is unreactive with mesityliodine diacetate, even under forcing acidic conditions. The symmetrical diphenyliodonium triflate was used to generate benzyne which was trapped with furan in 59% overall yield (3la; Scheme 3). Toluene, anisole, and diphenyl ether were all compatible under the standard conditions and generated trapped arynes in high overall yields (3ma, 3na, 3pa; Scheme 3). Several 1,2-disubstituted arenes were also compatible including those bearing functional groups that were not compatible with a thianthrenium leaving group, including triflate (1q), nitro (1s), phenyl (1t), and ester (1w) groups (3qa, 3sa, 3ta, 3wa; Scheme 3). We did not observe competitive loss of the triflate group in the case of 3qa (Scheme 3). In the case of a trifluoromethyl substituent, 1r-TT resulted in trace aryne adduct in our hands, though the isomer 4trifluoromethyl anisole has been successfully used by others. Additionally, aryl(Mes)iodonium reagent 1r-IMes yielded an approximate 10: 1 mixture of inseparable regioisomers due to competitive deprotonation at the 3-and 5position (Scheme 3). When we replaced furan with a nitrone 2c to trap the aryne, a similar mixture of regioisomers were formed, yet were separable by chromatography and the major one isolated in 76% overall yield from 1r (3rc, Scheme 3). We have noted previously that substitution patterns impact the reactivity of aryl "onium" aryne precursors, and those derived from 1,3-substituted arenes are the least reactive. We found that using the aryl(Mes)iodonium intermediates and LiHMDS as base Scheme 3. Increased scope of arenes via two-step net dehydrogenation with aryl(Mes)iodonium intermediates.