Photochemistry of N-Arylsulfonimides: An Easily Available Class of Nonionic Photoacid Generators (PAGs).

The photochemical behavior of differently substituted N-arylsulfonimides was investigated. Homolysis of the S-N bond took place as the exclusive path from the singlet state to afford both N-arylsulfonamides and photo-Fries adducts, the amount of which depended on reaction conditions and aromatic substituents. Sulfinic and sulfonic acids were released upon irradiation under deaerated and oxygenated conditions, respectively. The nature of the excited states and intermediates involved were proved by laser flash photolysis and EPR experiments. These results highlighted the potential of such compounds as nonionic photoacid generators able to photorelease up to two equivalents of a strong acid for each mole of substrate.