Catalytic Conversion Of Ketoacetic Acid To Pyridine

Amino acid is a kind of very important organic compounds with extensive applications in many areas including food science, medicinal chemistry and chemical industry. Enzymatic transamination of α-keto acids plays an important role in the synthesis of α-amino acids in biological system. Due to high price of transaminases and limited substrate scope, enzymatic transamination has little application for the synthesis of α-amino acids in organic chemistry and organic labs. Biomimetic transamination by using chiral pyridoxal and its derivatives as catalyst provides a new and attractive strategy for the synthesis of α-amino acids. The studies are not only theoretically important, but also have a practical potential.Pyridoxal and its derivatives are the catalysis center in enzymatic transamination. It has been proposed that deprotonation with base and protonation with acid occur during the catalytic cycle of enzymatic transamination. The participation of base and/or acid facilitates the transamination by lowering the activation energy of the reaction. Thus, introducing appropriate functional groups such as amine, acid, urea and so on onto pyridoxal might form more active catalysts for biomimetic transamination.In this thesis, we designed and synthesized a series of pyridoxals tagged with different functional groups. The pyridoxals exhibited high catalytic activity in transamination of α-keto acids, proving various amino acids in good yields. The transformation with some obvious advantages such as mild reaction conditions and easy operation represents a potentially practical method for the synthesis of α-amino acids.