Highly efficient chiral extraction of amino acid enantiomers using Wei-Phos-Pd as chiral extractant

The development of novel and highly efficient chiral extractants has always been a research hotspot in the field of chiral extraction. In this work, Wei-Phos, an adaptive chiral sulfinamide phosphine ligand featuring multiple coordination centers, was employed as a chiral extractant to separate amino acid enantiomers. The influences of metal precursors, organic solvents, pH of the aqueous phase, extractant concentrations, and extraction temperature on enantioselectivities were investigated. The results show that Wei-Phos-Pd is a highly efficient chiral extractant for amino acid enantiomers. D-amino acids are preferentially recognized by Wei-Phos-Pd. The separation factors for phenylalanine (Phe), homophenylalanine (Hph), 3-chlorophenylglycine (3-Cl-Phg), and 4-nitro-phenylalanine (4-NO2-Phe) are 12.19, 8.89, 13.17 and 7.06, respectively. The structure–activity study and recognition mechanism analysis indicate that the chiral tert-butylsulfinamide group and diphosphine structure in Wei-Phos have significant influences on enantioselectivities. The multiple coordination centers account for the high enantioselectivities of Wei-Phos. Wei-Phos-Pd stands out as the most efficient and versatile chiral diphosphine-metal extractant for chiral extraction of amino acids to date.