Study On Asymmetric Catalytic Conversion Of α - Ketone To Ammonium By A Novel Chiral Pyridoxamine Catalyst

Optically active α-amino acids are elementary structural units of polypeptides and proteins and broadly present in many natural products. They have been obtained extensive applications in many areas such as medicinal chemistry, agriculture and food science. In addition, α-amino acids also have been widely used as chiral auxiliaries or catalysts in organic synthesis. The development of new methods for the synthesis of α-amino acids is still an important and active topic in organic chemistry.Enzymatic transamination of α-keto acids is a vital reaction for the synthesis of amino acids in biological system. Vitamin B6 including pyridoxamine phosphate(PMP) and pyridoxal phosphate(PLP), the co-enzymes of transaminases, are catalysis center in enzymatic transamination. Development of biomimetic transamination by using chiral pyridoxamines or pyridoxals as catalyst might provide a new and efficient strategy for the synthesis of optically active amino acids. In this thesis, we designed and synthesized a variety of chiral pyridoxamines tagged with an amide chain. The pyridoxamines exhibited good catalytic activity and promising enantioselective control ability in transamination of α-keto acids, providing a mild, efficient and attractive way for the synthesis of optically active amino acids.The studies include the following three parts:(1) We designed and synthesized a series of chiral pyridoxamines derivatives.(2) The pyridoxamines catalysts were investigated in transamination of α-keto acids and reaction conditions were optimized.(3) Substrate scope was then examined under the optimized reaction conditions for the chiral- pyridoxamines-catalyzed transamination of keto acids.