Can Primary Arylamines Form Enamine? Evidence, α-Enaminone, and [3+3] Cycloaddition Reaction
Can Primary Arylamines Form Enamine? Evidence, α-Enaminone, and [3+3] Cycloaddition Reaction
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DOI：
10.1021/acs.joc.1c01462
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发表时间：
2021-10-05
影响因子：
3.6
通讯作者：
Wang, Hong
中科院分区：
文献类型：
--
作者：
Fernando, E. H. Nisala;Vazquez, Jose Cortes;Wang, Hong
用核磁共振波谱法检测并证实了伯芳胺生成烯胺的过程。自由基猝灭剂的存在，例如（2,2,6,6-四甲基哌啶-1-基）氧化基，被发现是检测烯胺形成所必需的。还研究了由伯芳胺和酮直接合成α -胺酮的方法。α -漆胺酮形成的机理研究表明，通过O-2单线态能量转移产生的胺自由基阳离子参与了α -漆胺酮形成的初始化。通过烯酮的[3+3]环加成反应，探索了α -胺酮的反应活性和利用价值，得到了收率为58 ~ 85%的二氢吡啶。-胺酮表现出一系列不同于胺类的反应性。在这项工作中获得的知识推进了我们对有机化学的基本理解，为烯胺催化提供了见解和新的机会。
The formation of enamine from primary arylamines was detected and confirmed by nuclear magnetic resonance spectroscopy. The presence of a radical quencher, e.g., (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, was found to be essential for the detection of enamine formation. A direct synthesis of alpha-enaminones from primary arylamines and ketones was also developed. Mechanistic investigation of alpha-enaminone formation suggests that an amine radical cation generated through O-2 singlet energy transfer was involved in initiating alpha-enaminone formation. The reactivity and utility of alpha-enaminones were explored with a [3+3] cycloaddition reaction of enones affording dihydropyridines in good yields (58-85%). alpha-Enaminones displayed a set of reactivities that is different from that of enamines. The knowledge gained in this work advances our basic understanding of organic chemistry, providing insights and new opportunities in enamine catalysis.