Abstract

The search for innovative and green reaction media is a prominent topic in the recent research in chemistry. Deep Eutectic Solvents (DESs) are currently gaining relevance in this field thanks to their unique properties in terms of their “greenness” as well as in terms of their catalytic properties. In this work we developed an efficient protocol for the conjugate aza-Michael addition of amines to 2-vinylpyridine using 14 differently structured acid DESs as both reaction media and catalysts, so preventing the use of other acid additives. The results are influenced by the acidity of the components of the DESs, showing the best results with weak acids in the DESs components, with isolated yields up to 86%. The aza-Michael reaction is a widely used synthetic route for the C–N bond formation in organic synthesis. In particular, the addition of amines to 2-vinylpyridine is used for the realization of pharmaceutically relevant compounds with anticancer, antiarrhythmic, and analgesic properties. Comparing the results with the ones observed in literature for the same reaction, this procedure revealed to be a convenient and efficient method for this relevant transformation.

Graphic abstract

中文翻译：

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探索不同结构的深共熔溶剂在将氮的氮杂-迈克尔加成至2-乙烯基吡啶中的酸性催化作用

摘要

在化学的最新研究中，寻求创新的绿色反应介质是一个突出的主题。由于其在“绿色”和催化性能方面的独特性能，深共晶溶剂（DES）目前在该领域越来越重要。在这项工作中，我们开发了一种有效的方案，使用14种不同结构的酸DES作为反应介质和催化剂，将胺类化合物在2乙烯基吡啶上进行氮杂-迈克尔共轭加成反应，从而防止了其他酸添加剂的使用。结果受DESs组分酸度的影响，显示DESs组分中弱酸的最佳结果，分离产率高达86％。氮杂-迈克尔反应是有机合成中C–N键形成的一种广泛使用的合成途径。尤其是，在2-乙烯基吡啶中添加胺可用于实现具有抗癌，抗心律不齐和止痛特性的药学上相关的化合物。将结果与文献中相同反应的结果进行比较，表明该方法是进行相关转化的便捷有效方法。

图形摘要