Excited-state configuration of nitroarenes enables oxidative cleavage of aromatics over alkenes.

The ozonolytic deconstruction of aromatics remains a challenge in organic chemistry. Ozone preferentially reacts with alkenes over arenes, meaning that once the initial aromatic cleavage occurs, the dearomatized products are inherently more reactive than the starting materials. Consequently, the process cannot be halted, resulting in full oxidation. Addressing this challenge requires subverting intrinsic rules of chemoselectivity to transform a less reactive substrate in the presence of a more reactive one. We demonstrate that this concept can be achieved by using photoexcited nitroarenes. Crucial to the success of this chemoselective process is the use of a nitroarene that is preferentially excitable to a triplet π,π* state over the n,π* state. This switch in excited-state configuration provides an otherwise inaccessible manifold, in which oxidative cleavage is diverted toward aromatics in the presence of alkenes. Editor's summary: One of the defining characteristics of aryl compounds such as benzene is their greater stability compared with other arrangements of carbon-carbon double bonds. If one of the aryl bonds is broken, those remaining tend to be more reactive. Olivier et al. report a reaction manifold that reverses this prevailing trend. A nitroarene reagent can be photoexcited to a state that preferentially reacts with arenes over olefins, likely through transient complexation, thereby enabling clean oxidative cleavage of just one aryl bond. —Jake S. Yeston [ABSTRACT FROM AUTHOR]