<i>N</i>-Phenyl-1,2,4-triazoline-3,5-dione (PTAD) as a Dienophilic Dinitrogen Equivalent: A Simple Synthesis of 3-Amino-1,2,4-benzotriazines from Arylcarbodiimides
作者:Mateo Alajarin、Baltasar Bonillo、Marta Marin-Luna、Pilar Sanchez-Andrada、Angel Vidal
DOI:10.1002/ejoc.200901103
日期:2010.2
N-Arylcarbodiimides react with PTAD to provide [1,2,4]triazolo[1,2-a][1,2,4]benzotriazines by a [4+2] cycloaddition reaction. When asymmetrically substituted diarylcarbodiimides are used, the cycloaddition proceeds with total chemoselectivity because only the more electron-rich aryl nucleus is involved. This observation has been rationalized by a computational study using DFT methods that shows that
N-芳基碳二亚胺与 PTAD 反应,通过 [4+2] 环加成反应生成 [1,2,4] 三唑并 [1,2-a][1,2,4] 苯并三嗪。当使用不对称取代的二芳基碳二亚胺时,环加成以总化学选择性进行,因为仅涉及更富电子的芳核。使用 DFT 方法进行的计算研究证明了这一观察结果,该研究表明,在 HTAD 与芳基碳化二亚胺的反应中,能垒的大小取决于芳核上取代基的电子特征;计算还表明反应通过具有极性特征的异步状态进行。用氢氧化钾处理最终的环加合物得到 3-芳基(烷基)氨基-1,2,4-苯并三嗪。