There is very little information in the literature on forming arynes from aryl sulfonium salts, 15 and we therefore considered different solvents, bases, and temperatures for this process (Table , entries 5-12). Toluene is the solvent we have selected for our standard conditions. Using 1,2-dichloroethane and dimethylformamide resulted in much lower yields of aryne adducts (Table and). However, ethereal solvents (dioxane and THF) and acetonitrile resulted in similar, but slightly lower yield than our standard conditions (Table ). The use of KO t Bu resulted in lower yield than NaO t Bu (cf. 48 vs 64%, Table , entries 9 and 10). Switching to LiHMDS as base decreased the yield of 2a as well (Table , entry 11). Weaker inorganic and organic bases (i.e., K2CO3 and NEt3) did not result in any observable formation of 2a. Lowering the reaction temperature to room temperature also reduced the yield of 2a (Table 1, entry 12). The conditions in entry 1 (toluene as solvent) and entry 8 (1,4-dioxane as solvent) were found to provide the highest overall yields and were used to evaluate the scope of the reaction. a Standard conditions: step 1 -chlorobenzene (6 mL), TTO (1.5 mmol, 1 equiv.), TfOH (2.25 mmol, 1.5 equiv.), TFAA (4.5 mmol, 3 equiv.), 25 °C, 92% yield; step 2 -1a(TT + ) -OTf (0.1 mmol, 1 equiv.), furan (0.5 mmol, 5 equiv.), NaO t Bu (0.2 mmol, 2 equiv.), toluene (0.5 mL), 65 °C, 1 hour, 81% yield. Yields are based on two-step process and determined from crude 1 H NMR spectrum of 2a with trimethoxybenzene as internal standard. c Used DBTO instead of TTO. d Based on 72% and 71% yield of 1a(DBT + ) -OTf and 2a, respectively. e Used MesI(OAc)2 instead of TTO in step 1. f Yield for step 1. g Yield for step 2, step 1 not conducted.