Recyclable (PhSe)2-catalyzed selective oxidation of isatin by H2O2: a practical and waste-free access to isatoic anhydride under mild and neutral conditions

After a series of careful conditional optimizations and catalyst screenings, a methodology to prepare isatoic anhydrides through organoselenium-catalyzed selective oxidation of isatins by H2O2 under mild and neutral conditions was developed. The reactions were very practical because of the recyclability of the catalyst and solvent and the convenient isolation procedures of the products. This work reports the organoselenium-catalyzed oxidation of heterocycles that greatly expands the application scopes of organoselenium catalysis. It also indicates that the organoselenium catalysts are robust enough to be recycled in industrial production if suitable isolation procedures are developed.