N-Arylation of isatins. A direct route to N-arylisatoic anhydrides

The synthesis of N-arylisatoic anhydrides 3 has been accomplished by using a two-step process. The key reaction in the sequence is the direct N-arylation of isatin with an aryl bromide in the presence of cupric oxide. Subsequent oxidation of the resulting N-aryl isatin 2 with m-chloroperoxybenzoic acid furnishes the desired products.