An efficient synthesis of pyrazine-based amidoximes bearing amino acid residues is reported. Esterification of amidoximes with further microwave-assisted cyclization into α-amino acid-derived 1,2,4-oxadiazoles has been developed. Conformational analysis of the obtained pseudopeptides by NMR and FTIR spectroscopy revealed intramolecular interactions due to the influence of a pyrazine ring and prolyl amide bond isomerization. The content of trans/cis conformers depending on the substitution at the pyrazine moiety for Pro-containing derivatives has been estimated.

中文翻译：

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新型的含pyr胺肟，a胺肟酯和1,2,4-恶二唑单元的吡嗪基假肽的合成和构象研究

报道了带有氨基酸残基的基于吡嗪的ox胺肟的有效合成。已经开发了将酰胺肟肟进一步微波辅助环化成α-氨基酸衍生的1,2,4-恶二唑的酯化反应。通过NMR和FTIR光谱对获得的假肽进行构象分析，发现由于吡嗪环和脯氨酰胺键异构化的影响，分子内的相互作用。已经估计了反式/顺式构象异构体的含量，取决于吡嗪部分上含Pro的衍生物的取代。