Iodoarene 1 (1.0 equiv) and m-CPBA (1.1 equiv) were dissolved in CH2Cl2 [0.2 M] in a round bottom flask. The flask was transferred to an ice bath at 0 °C followed by drop-wise addition of TfOH (2.0 equiv) with a Hamilton syringe. When the reaction mixture had stopped fuming, it was allowed to reach rt. The reaction was stirred for 10-60 min to ensure pre-oxidation of the iodine prior to introduction of the arene 2. Moderately electron rich 2ad can be added directly to the solution after the preoxidation time. Highly electron rich 2e-f require addition of H2O (2.0 equiv) and stirring for 5 min before the arene 2 was added to the solution. The reaction was then stirred at rt for 16 h. Upon completion of the reaction, the solvent was evaporated and products 3a-h were precipitated in Et2O and isolated by filtration. I BF 4 -3r 72% I -OTf 3s 76% I