Relative Rates for the Aminations of h3-Allyl and h3-Benzyl Complexes of Palladium

Reactions of nucleophiles with metal-bound hydrocarbyl π-ligands bound in an η³-fashion are key steps in a variety of carbon−carbon and carbon−heteroatom bond-forming reactions. To reveal factors that control the rates of reaction of nucleophiles with this type of ligand, the rates of reactions of an aromatic and an aliphatic amine with a series of η³-allyl, η³-benzyl, and η³-phenethyl palladium complexes ligated by the bisphosphine (R)-BINAP to form allylic and benzylic amines were measured. These data showed that the less common addition to an η³-benzyl complex is faster than the more common addition to an η³-allyl complex. The relative rates of reaction followed the trend naphthylmethyl > naphthylethyl > benzyl > 1,1-dimethylallyl > allyl. Computational studies suggest that there is a correlation between the amount of positive charge at the site of nucleophilic attack and the rate of C−N bond formation. Read more on publisher's site.