Modifiable Sulfur Tethers as Directing Groups for Aromatic CH Acetoxylation Reactions

A designed new class of modifiable sulfur tethers for aromatic CH bond functionalizations is presented. As a model, the palladium‐catalyzed directed acetoxylation reaction was studied. The more challenging sulfoxide tethers were the most effective in this transformation, showing a broad functionality tolerance, high S oxido‐redox stability and no catalyst poisoning. Preliminary mechanistic studies indicate that the higher reactivity and selectivity shown by the sulfoxide tethers vs. the corresponding sulfones can be attributed to an extra coordination of the sulfoxide S atom to the catalyst. The utility of the presented methodology to generate structurally interesting aromatic derivatives by a subsequent modification of the S‐tether is also exemplified.