Microwave-assisted photooxidation of sulfoxides

We demonstrated microwave-assisted photooxidation of sulfoxides to the corresponding sulfones using ethynylbenzene as a photosensitizer. Efficiency of the photooxidation was higher under microwave irradiation than under conventional thermal heating conditions. Under the conditions, ethynylbenzene promoted the oxidation more efficiently than conventional photosensitizers benzophenone, anthracene, and rose bengal. Ethynylbenzene, whose T-1 state is extremely resistant to intersystem crossing to the ground state, was suitable to this reaction because spectroscopic and related reported studies suggested that this non-thermal effect was caused by elongating lifetime of the T-1 state by microwave. This is the first study in which ethynylbenzene is used as a photosensitizer in a microwave-assisted photoreaction.

Automated summary

This study demonstrated the microwave-assisted photooxidation of sulfoxides to sulfones using ethynylbenzene as a photosensitizer. The efficiency of the reaction was higher under microwave irradiation compared to conventional thermal heating, with ethynylbenzene promoting oxidation more efficiently than traditional photosensitizers. Ethynylbenzene's resistance to intersystem crossing and elongation of the T-1 state's lifetime by microwave make it suitable for this non-thermal effect reaction, marking the first use of ethynylbenzene as a photosensitizer in a microwave-assisted photoreaction.