Photoactivated Formal [3 + 2] Cycloaddition of N-Aryl Cycloprop-ylamines

Organic transformations initiated by photochemical activation have been at the forefront of reaction discovery. We have seen the [2+2] photocycloaddition performed upon excitation of α,β-unsaturated carbonyl compounds, and more recently [3 + 2] cycloadditions of aryl cyclopropyl ketones have been reported. These methodologies required a photocatalyst and/or external activators, adding some limitations to the substrates used. Herein, we report a formal photochemical [3 + 2] cycloaddition using N-aryl cyclopropylamines and α,β-unsaturated carbonyl systems without the use of photocatalysts or additives. This simple method proceeding through a Single Electron Transfer (SET) offers a wide scope for the synthesis of N-arylaminocycloalkyl compounds in good to excellent yields.