Dynamic Thermodynamic Resolution of Unprotected Amino Acids Using Ni(II) Chiral Schiff Bases

Dynamic thermodynamic resolution of amino acids (AAs) using Ni(II) chiral Schiff bases is one of the simplest and most efficient methods to obtain optically active AAs. A comparison of the reactivity of 36 rac-AAs with the Ni(II) complex revealed that this method can be easily applied to dynamic thermodynamic resolution and S/R interconversion of AAs with unprotected active functional groups. It can also be really applied for the side-chain modification of AA derivatives with active functional groups on the Ni(II) complex. Furthermore, the antimicrobial activities of the synthesized Ni(II) complexes were evaluated, and the Ni(II) complexes [(S,S)-3 g, (S,S)-3 h, and (S,S)-3 i] showed remarkable antibacterial activity against Micrococcus luteus, a Gram positive bacterium. Dynamic thermodynamic resolution of racemic unprotected amino acids with the Ni(II) chiral Schiff base complex are described. This method can be easily applied to a variety of unprotected amino acids to obtain optical pure amino acids and the side chain modified amino acid derivatives. image