联苯胺
化学
质子化
取代基
化学选择性
西格玛反应
药物化学
阿齐林
立体化学
催化作用
戒指(化学)
有机化学
离子
出处
期刊:Current Organic Synthesis
[Bentham Science]
日期:2017-04-04
卷期号:14 (4): 511-530
被引量:6
标识
DOI:10.2174/1570179413666161021103952
摘要
The diversity and chemoselectivity in rearrangements of N,N’-diarylhydrazines are reviewed and summarized. The symmetric N,N’-diarylhydrazines without any para-substituents generally favor para-benzidine rearrangement accompanying diphenyline rearrangement, even semidine rearrangement in some cases, while those with single or double N-naphthyl(s) or double para-substituent phenyls undergo ortho-benzidine rearrangement accompanying ortho-semidine rearrangements occasionally because double and single nitrogen atom(s) are/is protonated. Some symmetric N,N’-diarylhydrazines with electron-withdrawing para-substituents take place predominately disproportionation reaction, resulting in the formation of the corresponding diaryldiazenes (azoarene compounds) and aromatic amines. However, unsymmetric N,N’-diarylhydrazines predominate semidine rearrangement(s) accompanied by the diphenyline rearrangement since electron-rich nitrogen atom is protonated favorably and non-protonated electron-poor nitrogen atom undergoes N[1,3] sigmatropic shift with inversion of the N atom configuration. Occurrence of ortho- and para-semidine rearrangements depends upon the substituted pattern of the unsymmetric N,N’-diarylhydrazines. Some N,N’-diarylhydrazines with strong electronwithdrawing substituents, especially para-substituents, are sensitive to air, favoring oxidation to generate azo product N,N’-diaryldiazenes. Keywords: Diarylhydrazines, rearrangement, chemoselectivity, benzidine, semidine, diphenyline.
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