Diaryliodonium salts (Ar2IX) are widely recognized as versatile electrophilic aryl sources in modern organic synthesis, and are increasingly applied in supramolecular and materials chemistry. Their exceptional balance of reactivity and stability enables their utilization in arylations of carbon and heteroatom nucleophiles under both metal-catalyzed and metal-free conditions. Diaryliodonium salts possess relatively low toxicity and can be used under mild conditions, which has positioned them as sustainable complements to conventional transition metal-catalyzed arylations. The easy accessibility of Ar2IX from commercial sources or through inexpensive synthetic routes is key to their popularity. One of the most convenient strategies to access them is by oxidation of iodoarenes 1 or elemental iodine under acidic conditions followed by an in situ ligand exchange with a suitable arene 2. Our group pioneered this field by presenting the first synthetically useful onepot protocol of this sort in 2007, demonstrating a broad substrate scope with m-CPBA as the oxidant (Scheme 1, Route A). To date, a variety of onepot procedures for the synthesis of Ar2IX are available, and the recent progress in the field has made it possible to attain rather complex examples of these reagents. Utilizing route A, the substitution pattern of R 1 and electronic properties of iodoarene 1 are highly flexible, and the success of the reaction is often dictated by the choice of acid to activate the oxidant. The triflic acid protocol has a significantly larger scope, and is generally required to achieve efficient iodine oxidation of electron-deficient iodoarenes 1. For neutral or electron-rich iodoarenes 1, the milder acid TsOH is sufficient, and sometimes preferred to avoid undesired oxidation of arene 2. As arene 2 is incorporated through an electrophilic aromatic substitution (EAS) pathway, it must possess appropriate EAS reactivity. This method provides the corresponding diaryliodonium triflate or tosylate 3-OTf/3-OTs with strong para-selectivity in regards to the (most) electron-donating R 2 -substituent.