Phosphorus acids as highly efficient promoters for the palladium-phenanthroline catalyzed carbonylation of nitrobenzene to methyl phenylcarbamate

A new family of promoters, based on phosphorus acids, is reported for the catalytic carbonylation of nitrobenzene to methyl phenylearbamate by palladium-phenanthroline complexes. With the new promoters, unprecedented reaction rates (TOF up to 6000/h) and catalyst stability (TON up to 10(5)) could be reached. The best promoter is phosphoric acid, which is also very cheap, nontoxic and easily separable from the reaction products.