Expeditious Photosensitized Oxidation Reaction of Sulfides Toward the Selective Preparation of Sulfoxides and Sulfones

The singlet oxygen‐photosensitized oxidation reaction of a series of dialkyl and alkylaryl sulfides was investigated under steady‐state conditions irradiating with white LEDs in the presence of molecular oxygen and different solvents, with the aim of synthesizing the corresponding sulfoxides and sulfones with high chemoselectivity and in good‐to‐excellent yields. Two synthetic methodologies were developed. In Method A, the photoreaction was performed in methanol and proved to be the optimal for the exclusive formation of sulfoxides, affording yields up to 98% without detectable overoxidation to sulfone after only 20 min of reaction time. In Method B, acetonitrile was employed as the solvent, leading to the chemoselective synthesis of sulfones in yields up to 85% after 30 min of irradiation time. These photochemical approaches offer significant advantages for the synthesis of sulfoxides and sulfones, providing an alternative, operationally simple, and convenient method. The use of DABCO as the physical quenching of the in situ photogeneration of singlet oxygen promoted the inhibition of the photoreaction and the co‐oxidation of chemical trap diphenylsulfoxide (Ph ₂ SO) demonstrates that the key intermediate is the nucleophilic persulfoxide that decays to the electrophilic thiodioxirane intermediate. The experimental evidences led to propose a plausible reaction mechanism.