Triplet Excited Nitroarene Converts Aryl Alkynes to Ketones by Deleting a Carbon Atom.

In this study, triplet excited nitroarenes were used to convert internal alkynes to ketone fragments through simultaneous oxygen insertion and carbon deletion. The approach was effective across 33 diverse substrates, compatible with various functional groups, and applicable to bioactive molecule derivatives and large-scale synthesis. UV-vis spectroscopy revealed the role of visible light in exciting nitroarenes, while mechanistic experiments identified ketene and nitrosoarene as key intermediates, with the deleted carbon released as CO and CO2.