Direct photochemical route to azoxybenzenes via nitroarene homocoupling

<p>We report on a direct photochemical method for the one-pot, catalyst- and additive-free synthesis of azoxybenzene and substituted azoxy derivatives from nitrobenzene building blocks. This reaction is conducted at room temperature and under air, and can be applied to substrates with a wide range of substituents. Yields of products derived from <em>para</em>- and <em>meta</em>-substituted nitrobenzenes are typically good, while sterically encumbered <em>ortho</em>-substituted substrates are not as fruitful. Photochemical Wallach rearrangement of generated azoxybenzenes to <em>ortho</em>-hydroxyazoxybenzenes was observed in some cases, most markedly in selected <em>ortho</em>-halogenated nitrobenzenes. Overall, this method provides an efficient, green pathway to highly value-added azoxybenzene products.</p>