A synthetic protocol for the preparation of α-acyl aminocarboxamides and α-amino amidines is proposed. The selectivity toward each of these two possible products was tuned by simple modifications of the reaction conditions. A broad scope is presented, allowing access to the desired products in up to 87% (Ugi adduct) and 93% (α-amino amidine). Theoretical calculations were carried out, and the analysis led to the proposal of a new mechanistic pathway for the Ugi reaction, in which methanol acts not only as the solvent but also as a reagent. High-resolution (tandem) mass spectrometry experiments allowed the detection and characterization of the key intermediate associated with this new and alternative reaction pathway, thus supporting the theoretical proposal.

中文翻译：

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Ugi 多组分反应的溶剂依赖性竞争机制：α-酰基氨基甲酰胺与 α-氨基脒形成的联合理论和实验研究

提出了一种制备α-酰基氨基甲酰胺和α-氨基脒的合成方案。通过对反应条件的简单修改来调整对这两种可能产物的选择性。提供了广泛的范围，允许获得高达 87%（Ugi 加合物）和 93%（α-氨基脒）的所需产品。进行了理论计算，分析导致提出了 Ugi 反应的新机制途径，其中甲醇不仅充当溶剂，还充当试剂。高分辨率（串联）质谱实验允许检测和表征与这种新的替代反应途径相关的关键中间体，从而支持理论建议。