One Stone Two Birds—Enantioselective Bimetallic Catalysis for <scp>α‐Amino</scp> Acid Derivatives with an Allene Unit

Abstract

Main observation and conclusion A highly enantioselective 2,3‐allenylation of acyclic and cyclic α‐imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available ( R , R p )‐ i Pr‐FOXAP (also as Phosferrox, ( R , R )‐[2‐(4’‐ i ‐propyloxazolin‐2’‐yl)ferrocenyl]diphenyl phosphine) ligand for both metals affording optically active 2,3‐butadienyl α‐amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed. The synthetic versatility of this reaction has been demonstrated by gram‐scale synthesis, a catalytic enantioselective synthesis of naturally occurring ( S )‐2‐amino‐4,5‐hexadienoic acid A, and conversions to several useful chemicals, such as optically active α‐amino acids, β‐amino alcohols, potential chiral oxazoline ligands bearing an allenic moiety, and bicyclic ketone compounds. A mechanism involving the roles of two metals and the single chiral ligand has been extensively studied based on the isolation of key palladium pre‐catalyst and control experiments.