Catalytic Asymmetric Synthesis of α-Allyl α-Tertiary Aminoesters from α-Iminoesters and “Umpoled” π-Allyl Co Nucleophiles

Chiral α-tertiary aminoesters bearing an α-allyl substitution are highly sought after molecules in biochemistry and medicinal chemistry studies. Herein, we describe a catalytic asymmetric synthetic method to acquire these functional molecules from α-iminoesters and allylic carbonates. Under the catalysis of cobalt and spiropyrrolidine-derived amino-oxazoline ligands, the electrophilic allyl-Co(III) complex was umpoled to a nucleophilic allyl-Co(II) complex in reductive conditions, enabling a highly enantioselective nucleophilic addition. This approach provides a novel entry to α-tertiary aminoesters with versatile α-substituents with respect to either benzyl, alkyl, or allyl groups. Preliminary mechanistic investigations and density functional theory (DFT) studies suggest an allyl transfer process with initial chelation of the Co(II) complex with the α-iminoester, which might account for the regio- and enantioselectivity of this reaction.