Two complementary pathways for the preparation of N-substituted 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides (5) were proposed and successfully realized in the synthesis of 20 representative examples. These methods use the same types of starting materials viz. succinic anhydride, aminoguanidine hydrochloride, and a variety of amines. The choice of the pathway and sequence of the introduction of reagents to the reaction depended on the amine nucleophilicity. The first pathway started with the preparation of N-guanidinosuccinimide, which then reacted with amines under microwave irradiation to afford 5. The desired products were successfully obtained in the reaction with aliphatic amines (primary and secondary) via a nucleophilic opening of the succinimide ring and the subsequent recyclization of the 1,2,4-triazole ring. This approach however failed when less nucleophilic aromatic amines were used. Therefore, an alternative pathway, with the initial preparation of N-arylsuccinimides and their subsequent reaction with aminoguanidine hydrochloride under microwave irradiation, was applied. The annular prototropic tautomerism in the prepared 1,2,4-triazoles 5 was studied using NMR spectroscopy and X-ray crystallography.

中文翻译：

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3-(5-amino-1H-1,2,4-triazol-3-yl)丙酰胺的合成及其互变异构†

提出了两条互补的制备N-取代的 3-(5-amino-1 H -1,2,4-triazol-3-yl)丙酰胺 ( 5 ) 的途径，并在 20 个代表性实例的合成中成功实现。这些方法使用相同类型的起始材料，即。琥珀酸酐、氨基胍盐酸盐及多种胺类。将试剂引入反应的途径和顺序的选择取决于胺的亲核性。第一条途径从制备N-胍基琥珀酰亚胺开始，然后在微波照射下与胺反应得到5. 通过琥珀酰亚胺环的亲核开环和随后的 1,2,4-三唑环的再循环，在与脂肪胺（伯胺和仲胺）的反应中成功获得了所需的产物。然而，当使用较少亲核芳族胺时，这种方法失败了。因此，采用了一种替代途径，即首先制备N-芳基琥珀酰亚胺，然后在微波照射下与氨基胍盐酸盐反应。使用NMR光谱和X射线晶体学研究了制备的1,2,4-三唑5中的环状原质互变异构。