Ligand Exchange in Mixed Organocuprate(I) π-Complexes

π-Complexes of mixed organocuprate(I) reagents with α,β-unsaturated carbonyl compounds can undergo ligand exchange to give the corresponding homocuprate–olefin π-complexes. The mechanism of this metathesis, which has profound implications for synthetic applications, involves a second-order reaction of the mixed cuprate with the mixed cuprate–olefin π-complex.