Innovative Structure Conversion of Optically Active Amino Acids by Electrochemical Oxidation and Its Utilization in Organic Synthesis

光学纯有机化合物的合成是当前有机合成研究的热点之一。在这项研究中，电化学氧化被用作将容易获得的α-氨基酸转化为新的光学活性中间体的关键步骤，这些中间体在有机合成中进一步阐述，如下所述。(1)以L-蛋白质和L-赖氨酸衍生物为原料，采用电化学氧化法制备了光学活性的α-烷基脯氨酸和α-烷基哌啶酸衍生物。(2)以L-赖氨酸衍生物为原料，通过电化学氧化制备氧化产物，制备了光学活性的无环ω-羧基-α-烷基-α-氨基酸和新型光学活性助剂。(3)以L-缬氨酸为原料，通过N-苯乙酰基恶唑烷酮与α-甲氧基哌啶衍生物形成碳-碳键，高对映选择性地合成了光学活性β-氨基酸（d-苏型哌甲酯）。(4)探索了适合Hofmann重排反应的新反应条件。通过使用电化学方法创建反应条件，其中使用2，2，2-三氟乙醇（TFEOH）作为溶剂。在该反应条件下，L-谷氨酰胺酯衍生物有效地转化为2，4-二氨基丁酸酯，而不损失原始光学纯度。此外，三氟乙氧基羰基胺，在TFEOH中的霍夫曼重排产物，被发现是不对称脲的前体。(5)在某些光学活性环状α-氨基酸的非Kolbe反应中观察到手性记忆现象。(6)开发了一种有效的环氨基化合物Cα-Cβ键的开环试剂，并将其应用于L-哌啶酸衍生物的开环反应。

Synthesis of optically pure organic compounds is one of topics in current organic synthesis. In this study, electrochemical oxidation was used as a key step for the transformation of easily available α-amino acids to new optically active intermediates, which were further elaborated in organic synthesis as described below.(1) L-Protein and L-lysine derivatives were converted to optically active α-alkylproline and α-alkylpipecolinic acid derivatives by using electrochemical oxidation as a key step. (2) Optically active acyclic ω-carboxyl-α-alkyl-α-amino acids and new optically active auxiliary were prepared through oxidation products that were prepared by electrochemical oxidation of L-lysine derivative. (3) Optically active β-amino acid (d-threo-methylphenidate) was prepared with a high enantioselectivity by the carbon-carbon bond formation between a-methoxypiperidine derivative and N-phenylacetyloxazolidinone prepared from L-valine. (4) A new reaction condition appropriate to the Hofmann rearrangement was exploited. The reaction condition was created by using an electrochemical method in which 2,2,2-trifluoroethanol (TFEOH) was used as a solvent. Under the reaction condition, L-Glutamine ester derivative was efficiently converted to 2,4-diaminobutyric acid ester without a loss of the original optical purity. Furthermore, tirflouroethoxycarbonylamines, the Hofmann rearrangement products in TFEOH, were found to be precursors for unsymmetrical ureas. (5) Memory of chirality was observed in the non-Kolbe reaction of some kinds of optically active cyclic α-amino acids. (6) An efficient reagent for the Cα-Cβ bond of cyclic amino compounds was exploited and it was applied to the ring opening of L-pipecolinic acid derivative.