Delineating the Mechanism of Ionic Liquids in the Synthesis of Quinazoline-2,4(1<i>H</i>
,3<i>H</i>
)-dione from 2-Aminobenzonitrile and CO<sub>2</sub>
作者:Martin Hulla、Sami M. A. Chamam、Gabor Laurenczy、Shoubhik Das、Paul J. Dyson
DOI:10.1002/anie.201705438
日期:2017.8.21
Ionic liquids (ILs) are versatile solvents and catalysts for the synthesis of quinazoline‐2,4‐dione from 2‐aminobenzonitrile and CO2. However, the role of the IL in this reaction is poorly understood. Consequently, we investigated this reaction and showed that the IL cation does not play a significant role in the activation of the substrates, and instead plays a secondary role in controlling the physical
离子液体(ILs)是用于从2-氨基苄腈和CO 2合成喹唑啉-2,4-二酮的通用溶剂和催化剂。然而,人们对IL在该反应中的作用了解甚少。因此,我们研究了该反应,结果表明IL阳离子在底物的活化中不发挥重要作用,而在控制IL的物理性质中起次要作用。IL阴离子(共轭酸)的p K a与反应速率之间存在线性关系,在ap K a处观察到最大的催化剂效率DMSO中的> 14.7。碱催化的反应受到喹唑啉-2,4-二酮产物的酸度的限制,该产物的酸度被更多的碱性催化剂去质子化,从而导致喹唑啉化物阴离子(共轭酸p K a 14.7)的形成。原始催化剂的中和反应和喹唑内酯阴离子催化剂的形成导致观察到的反应极限。