title: Asymmetric Synthesis of Chiral α-Methyl-α,β-diamino Acid Derivatives via Group-Assisted Purification Chemistry Using N-Phosphonyl Imines and a Ni(II)-Complexed Alanine Schiff Base.
abstract: The Mannich reaction between chiral N-phosphonyl imines and a Ni(II)-complexed alanine Schiff base (Ala-Ni) is reported. With a chiral phosphonyl auxiliary, a single isomer of α-methyl-α,β-diamino acid derivative containing vicinal chiral centers, including a chiral quaternary carbon center, can be obtained simply by washing the crude mixture with cosolvents. The absolute stereochemistry of the enantiomerically pure product has been unambiguously determined by X-ray crystallographic analysis.
authors.affiliation: Institute of Chemistry and BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Haowei
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Chemistry and BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.affiliation: Institute of Chemistry and BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute of Chemistry and BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Hongjian
authors.initials: H
authors.lastname: Lu
authors.affiliation: Institute of Chemistry and BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.|Department of Chemistry and Biochemistry, Texas Tech University , Lubbock, Texas 79409-1061, United States.
authors.forename: Guigen
authors.initials: G
authors.lastname: Li