Stereodivergent Pd/Cu Catalysis for the Dynamic Kinetic Asymmetric Transformation of Racemic Unsymmetrical 1,3-Disubstituted Allyl Acetates

A stereodivergent
Pd/Cu catalyst system has been developed for
the unprecedented dynamic kinetic asymmetric transformation (DyKAT)
of racemic unsymmetrical 1,3-disubstituted allylic acetates with prochiral
aldimine esters. A series of α,α-disubstituted α-amino
acids bearing vicinal stereocenters were easily prepared with excellent
enantioselectivities (up to >99% ee) and diastereoselectivities
(up
to >20:1 dr). Moreover, all four stereoisomers of the product can
be readily obtained simply by switching the configurations of the
two chiral metal catalysts. Furthermore, the present work highlights
the power of synergistic Pd/Cu catalysis consisting of two common
bidentate chiral ligands for stereodivergent synthesis.