Transition-Metal-Catalyzed Synthesis of Organophosphorus Compounds Involving P-P Bond Cleavage

Organophosphorus compounds are used as drugs, pesticides, detergents, food additives, flame retardants, synthetic reagents, and catalysts, and their efficient synthesis is an important task in organic synthesis. To synthesize novel functional organophosphorus compounds, transition-metal-catalyzed methods have been developed, which were previously considered difficult because of the strong bonding that occurs between transition metals and phosphorus. Addition reactions of triphenylphosphine and sulfonic acids to unsaturated compounds in the presence of a rhodium or palladium catalyst lead to phosphonium salts, in direct contrast to the conventional synthesis involving substitution reactions of organohalogen compounds. Rhodium and palladium complexes catalyze the cleavage of P-P bonds in diphosphines and polyphosphines and can transfer organophosphorus groups to various organic compounds. Subsequent substitution and addition reactions proceed effectively, without using a base, to provide various novel organophosphorus compounds.