The inherent defects,such as low enzymatic stability,short half-life and low tissue permeability have hampered the clinical application of natural peptide drugs.Studies exhibit that peptides containing quaternary α-amino acids tend to have increased hydrophobicity,as well as increased stability toward both chemical and metabolic decompositions,which lead them intriguing tools for the design and modification of peptides and proteins.The significance of quaternary α-amino acids has sparked the development of various enantioselective strategies for their synthesis[1].