Initially, we focused on developing a mild oxidation procedure starting from the iodoarene precursors. Previous studies on five-membered heteroaromatic iodonium salts revealed meta-chloroperoxybenzoic acid (mCPBA) as the oxidant of choice in the presence of triflic acid (TfOH). Based on those promising results, conditions were optimized using ortho-benzimidazole-substituted iodoarenes 4aa and 4ah (Table ).