Synthesis of Enantiomerically Enriched Non-Proteinogenic alpha-Amino Acids Using the Suzuki Reaction

Herein we report the synthesis of a variety of new enantiomerically enriched non-protein (S)-a-amino acids based on the reaction of generating new carbon-carbon bonds in the side chain group of the amino acid moiety with high chemical yields and optical purity using the reaction of Suzuki. As the initial synthon, the Schiff base Ni(II) complex of the chiral auxiliary (S)-BPB (N-benzyl proline benzophenone) and 4-bromo-L-phenylalanine amino acid was used. The final Ni(II) complexes were decomposed with aqueous HCl and the amino acids were isolated with excellent enantioselectivities (> 99% ee). The chiral auxiliary ligand (S)-BPB can be recycled and reused for the synthesis of starting Ni(II) complex.