Preparation of phenols by phthaloyl peroxide–mediated oxidation of arenes

Dionicio Siegel et al. provide detailed instructions on implementing their facile, scalable, catalyst-free and functional group–tolerant approach to hydroxylating arenes. This protocol describes an approach to installing hydroxyls into arenes through the direct replacement of C–H bonds with C–O bonds. This direct oxidation avoids the need to prefunctionalize the substrate, use precious metals, introduce directing groups, or use strong Brønsted or Lewis acids. Phthaloyl peroxide, the sole reagent used for this transformation, can be prepared readily from the commodity chemicals phthaloyl chloride and sodium percarbonate. Phthaloyl peroxide oxidizes a diverse range of arenes, and the reactions that involve its use are characterized by high functional group compatibility, which enables the hydroxylation of simple arenes, advanced synthetic intermediates, natural products and other drug-like molecules forming the corresponding phenolic compounds. Notably, the reaction is operationally straightforward and has no special requirements for the exclusion of oxygen and water. The synthesis of phthaloyl peroxide takes 4 h and the subsequent hydroxylation of mesitylene takes 21 h.