Palladium-Based Supramolecularly Regulated Catalysts for Asymmetric Allylic Substitutions

Herein is reported the effect of different polyether binders (alkali metal, alkaline earth metal, and lanthanide salts) as regulation agents to enhance the catalytic properties of palladium complexes derived from enantiopure bisphosphite ligands in allylic substitutions. The addition of RbOAc or M­(OTf)x (M = Mg2+, La3+, or Ho3+) led to positive effects in enantioselectivity (by up to 16% ee) for the allylic substitution reactions. These ligands coordinated in the usual cis-fashion or in an unprecedented trans-fashion to the palladium center, depending on the phosphite group, and presented different reactivity in the allylic substitutions.