<br>了解 N,N'-二酰肼的顺式-反式酰胺键异构化，以制定先验预测其最稳定溶液构象异构体的指南,The Journal of Organic Chemistry

当前位置： X-MOL 学术 › J. Org. Chem. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

了解 N,N'-二酰肼的顺式-反式酰胺键异构化，以制定先验预测其最稳定溶液构象异构体的指南
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2023-01-26 , DOI: 10.1021/acs.joc.2c01891
Jugal Kishore Rai Deka ₁ , Biswajit Sahariah ₁ , Bani Kanta Sarma ₁

Affiliation

N , N '-二酰肼（R ₁ CO-NR ₃ -NR ₄ -COR ₂ ）是一类在化学和生物学领域具有广泛应用的小分子。它们在结构上是独特的，因为它们的两个酰胺基团通过 N-N 单键连接，因此，这些分子可以以八种不同的异构形式存在。其中四种是由 C-N 键产生的酰胺异构体 [反式-反式 (t-t)、反式-顺式 (t-c)、顺式-反式 (c-t) 和顺式-顺式 (c-c)]限制旋转。此外，由于N-N键限制旋转，这些酰胺异构体中的每一种都可以以两种不同的异构体形式存在，特别是当R ₃和R ₄基团相对较大时。在此，我们结合溶液核磁共振波谱、X射线晶体学和密度泛函理论计算，系统地研究了 55 N , N'-二酰基肼的构象。我们的数据表明，当氮原子上的取代基R ₃和R ₄都是氢时。这些分子更喜欢扭曲的反式-反式 (t-t) (>90%) 几何形状 (H-N-C=O ∼ 180°)，而N-烷基化和N , N '-二烷基化分子更喜欢扭曲的反式-顺式 ( t–c) 几何形状。在这里，我们根据空间和立体电子效应分析了这些分子的各种异构体的稳定性。我们提供了仅通过检查其取代基 (R ₁ -R ₄ ) 即可先验预测N , N '-二酰肼最稳定构象异构体的指南。

"点击查看英文标题和摘要"

Understanding the Cis–Trans Amide Bond Isomerization of N,N′-Diacylhydrazines to Develop Guidelines for A Priori Prediction of Their Most Stable Solution Conformers

N,N′-diacylhydrazines (R₁CO-NR₃-NR₄-COR₂) are a class of small molecules with a wide range of applications in chemistry and biology. They are structurally unique in the sense that their two amide groups are connected via a N–N single bond, and as a result, these molecules can exist in eight different isomeric forms. Four of these are amide isomers [trans–trans (t–t), trans–cis (t–c), cis–trans (c–t), and cis–cis (c–c)] arising from C–N bond restricted rotation. In addition, each of these amide isomers can exist in two different isomeric forms due to N–N bond restricted rotation, especially when R₃ and R₄ groups are relatively bigger. Herein, we have systematically investigated the conformations of 55 N,N′-diacylhydrazines using a combination of solution NMR spectroscopy, X-ray crystallography, and density functional theory calculations. Our data suggest that when the substituents R₃ and R₄ on the nitrogen atoms are both hydrogens. These molecules prefer twisted trans–trans (t–t) (>90%) geometries (H–N–C═O ∼ 180°), whereas the N-alkylated and N,N′-dialkylated molecules prefer twisted trans–cis (t–c) geometries. Herein, we have analyzed the stabilization of the various isomers of these molecules in light of steric and stereoelectronic effects. We provide a guideline to a priori predict the most stable conformers of the N,N′-diacylhydrazines just by examining their substituents (R₁-R₄).

更新日期：2023-01-26

点击分享查看原文

点击收藏

阅读更多本刊新发论文