Aza-peptides are peptide analogs with potential applications as drug candidates. However, due to difficulties associated with the synthesis of these compounds, information regarding their bioactivity is very limited. Herein, we identify steric hindrance as one reason for the slowness of the aza-peptide bond formation reaction. The steric effect of the side group of amino acids in their coupling with the semicarbazide moiety in the synthesis of a model peptide, H-AA-AzAla-Phe-NH₂, was studied and quantified using COMU as a coupling reagent. Characterization of the role of this structural factor in aza-peptide bond synthesis is essential for outlining a new and efficient synthesis protocol.

氮杂肽是作为药物候选物具有潜在应用的肽类似物。然而，由于与这些化合物的合成有关的困难，关于其生物活性的信息非常有限。在本文中，我们确定空间位阻是氮杂-肽键形成反应缓慢的原因之一。使用COMU作为偶联剂，研究并定量了在合成模型肽H-AA-AzAla-Phe-NH _2中，氨基酸侧基与氨基脲部分偶联的空间效应。表征该结构因子在氮杂-肽键合成中的作用对于概述新的有效合成方案是必不可少的。