Anticipating Natural Phenolics Through Visible Light-Induced Photorearrangement of Quinones

A general protocol for the photorearrangement of substituted benzo- and naphthoquinones using monochromatic blue light irradiation in solution was developed. During this process, the quinone ring is transformed into the hydroquinone, while the substituent undergoes desaturation or annulation onto the proximal oxygen of the formed hydroquinone. We found that desaturation was preferred for acyclic saturated substituents, such as alkyl groups, and the tendency for annulation was observed for both cyclic and acyclic unsaturated substituents (allyl, alkenyl, aryl). The diversity of the participating substituents and the functional group tolerance of this transformation allowed us to prepare 10 natural phenolic compounds, suggesting that visible light may likewise induce their formation from the respective quinones in natural sources.