π‑Coordinating Chiral Primary Amine/Palladium Synergistic Catalysis for Asymmetric Allylic Alkylation

We report an arene-containing chiral
primary amine as a dual aminocatalyst and ligand: the π-coordinating
aminocatalyst/palladium synergistic catalysis for asymmetric allylic
alkylation of α-branched β-ketocarbonyls. The use of arene-containing
chiral primary amine catalyst led to not only enhanced reaction rate
but also reversed chiral induction compared with its sterically bulky
derivative. Both enantiomers of the allylic adducts bearing acyclic
all-carbon quaternary stereocenters could be obtained from the same
configured chiral aminocatalysts with high efficiency and excellent
regio-, stereo-, and enantioselectivity. Mechanistic studies revealed
a distinctive Pd-arene π-coordination mode for effective catalysis.
The π-coordinating chiral primary amine catalyst could be successfully
applied in the asymmetric allylation reactions of vinylethylene carbonates,
vinyl epoxides, or simple allylic alcohols.