One‐Step Synthesis of Donor‐Substituted Symmetric and Unsymmetric Trityl Cations from Arenes and Benzoic Acids

Herein, it is reported that reacting electron‐rich arenes and benzoic acids with trifluoromethanesulfonic anhydride gives convenient one‐step and one‐pot access to triphenylmethylium trifluoromethanesulfonates. This method enables the straightforward formation of these useful Lewis acids without external C1 sources. Three examples are isolated with one preparation upscaled to give 3 g of the trityl salt. Control experiments support a Friedel–Crafts acylation–alkylation sequence as the formation mechanism. Interestingly, the first Friedel–Crafts acylation is reversible, indicating a hydrolyzable CC bond. These findings are envisioned to help design future synthetic processes to form trityl cation‐based Lewis acids.