Triplet Excited Nitroarene Converts Linear Alkynes to Bent Ketones by Deleting a Carbon Atom

Abstract

Alkynes are rarely modified using visible light catalysis employing molecular editing techniques. In this work, we utilized triplet excited nitroarenes to transform linear alkyne topology to bent ketone fragments. The process involves the concurrent insertion of an oxygen atom and the detection of a carbon atom. The effectiveness and broad applicability of this approach were demonstrated through its successful application across diverse substrates (31 examples), compatibility with various functionalities and the modification of bioactive molecules, scalability in large-scale synthesis in continuous flow, and the synthesis of commercially available drug molecules. UV-vis spectroscopic studies unveiled the role of visible light in exciting the nitroarene in its triplet state. Preliminary mechanistic experiments by various kinetic and control experiments elucidated ketene and nitrosoarene as the key intermediates. The deleted carbon is released as CO and CO2 gases.