Revisiting Reaction Mechanism of Regioselective Disulfide-Catalyzed Photocatalytic Aerobic Oxidative Cleavage of 1-Arylbutadienes: A Computational Study

A computational study of the regioselective aerobic oxidative cleavage of 1-arylbutadienes is carried out employing density functional theory and high-level coupled-cluster methods, such as coupled-cluster singles and doubles with perturbative triples [CCSD(T)]. The results demonstrate that the reaction proceeds either via the intramolecular reduction or dimerization of peroxyl radical. These findings are in contrast to a previously proposed mechanism that progresses via formation of the dioxetane ring. The computations further indicate that the homolysis of S-S bond of diaryl disulfide derivatives cannot be achieved by irradiation with direct visible light under the reaction conditions due to the high bond dissociation energy.