Phosphites, phosphorus-palladium complexes

Cyclometalation is one of the most reliable and versatile methods for the synthesis of stable Pd-C a-bonds. In this reaction, a palladium (or other metal) complex is reacted with a ligand possessing a donor atom. The metal is directed by the donor atom to insert into a C-H bond, forming a chelate ring. This donor is usually the nitrogen of a tertiary amine, heterocyclic amine, or imine, or a phosphorus in a tertiary phosphine or phosphite. Other donor atoms, such as O and S, are occasionally encountered. The chelate ring size is normally five. ... 

TABLE 3. Some Achiral Phosphines and Phosphites Incorporated in Synthetically Useful Palladium-Phosphorus Complexes... 

Derivatives of carbohydrates that have been used to complex with rhodium catalysts to promote asymmetric hydrogenation include the phosphorus derivatives (6) and (7)/ and (8) (12) synthesized by esterification of the hydroxy-compounds with the appropriate phosphonyl chloride. Treatment of 7r-allyl-palladium chloride with the phosphite ester (13) gave a complex that was an enantioselective catalyst for hydrogenation of unsaturated acids and esters. ... 

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