Application of Nickel(II) Complexes to the Efficient Synthesis of ?- or ?-Amino Acids

Abstract

Nonproteinogenic ?- or ?-amino acids have attracted tremendous attention, as they are widely utilized for biological, biochemical, pharmaceutical, and asymmetric chemical investigations. Recently, we developed a series of new strategies for preparing achiral and chiral nickel(ii) complexes for the synthesis of amino acids. We applied these new methods utilizing chiral nickel(ii) complexes for the asymmetric Mannich reaction to synthesize enantiopure ?,?-diamino acids, the enantioselective tandem conjugate addition–elimination reaction to prepare glutamic acid derivatives, the Suzuki coupling reaction to yield ?2-amino acid derivatives, the asymmetric Mannich reaction to synthesize 3-aminoaspartate, the asymmetric Michael addition reaction to give ?-substituted-?,?-diaminobutyric acid derivatives, the asymmetric alkylation reaction to prepare linear ?-trifluoromethyl containing amino acids, and the asymmetric Michael addition reaction to synthesize syn-?-substituted tryptophans.