Design of Phosphine-Heteroarenesulfonamide Ligands as Dinuclear Silver Catalysts for Enantioselective Construction of α,β-Diamino Acids.

We designed and developed a phosphine-heteroarenesulfonamide ligand and found that it functions as a chiral dinuclear silver catalyst capable of cooperatively activating both nucleophiles and electrophiles. As a result, a highly enantioselective Mannich-type reaction between glycinate Schiff bases and acyclic ketiminoesters, unattainable by mononuclear catalytic systems, was achieved, affording α,β-diamino acid derivatives bearing tetrasubstituted chiral carbon centers in excellent yields and enantioselectivities. The resulting α,β-diamino acid derivatives were readily transformed into optically active 2-imidazolidinone and a dipeptide. Comprehensive mechanistic studies combining global reaction route mapping (GRRM), artificial force-induced reaction (AFIR), and density functional theory calculations revealed a cooperative bimetallic transition-state architecture responsible for the observed stereocontrol. These findings establish a new design principle for asymmetric catalysis based on homodinuclear activation and highlight the potential of dinuclear silver catalysis for the construction of complex chiral molecules.