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.