Asymmetric Reductive Cross-Coupling of Aldimines

Unsymmetrical chiral 1,2-diamines are important motifs widely present in pharmaceuticals, chiral auxiliaries, and ligands/catalysts. A novel and efficient strategy for the modular synthesis of unsymmetrical chiral 1,2-diaryl ethylenediamines via chiral diboron-templated reductive cross-coupling of aldimines has been established. By leveraging both steric and concentration effects, good chemoselectivity and enantioselectivity have been achieved and homocoupling side-reactions are effectively inhibited. The method exhibits good functional group tolerance and scalability, offering a practical and versatile route to unsymmetrical chiral 1,2-diamines.