N,N-bis(silyloxy) 酶胺的结构和立体动力学
Alexander A Tishkov1, Alexander D Dilman, Valery I Faustov
1N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Leninsky Prosp. 47, Moscow, Russian Federation. tishkov@cacr.ioc.ac.ru
Journal of the American Chemical Society
|September 19, 2002
概括
这项研究模拟了N,N-bis(silyloxy) 酶,揭示了它们独特的结构和立体动力学. 计算和物理方法证实了低C-N旋转障碍和高金字塔性,解释了它们的反应性.
科学领域:
- 有机化学 有机化学
- 计算化学的计算化学
- 物理化学 物理化学
背景情况:
- N,N-bis(silyloxy) 酶胺是一种新型的高度反应性化合物.
- 了解它们的结构和动态特性对于合成应用至关重要.
研究的目的:
- 为了阐明N,N-bis(silyloxy) 酶胺的结构和立体动力学.
- 将计算发现与实验光谱和晶体学数据相关联.
主要方法:
- 密度函数理论 (DFT) PBE/TZP方法用于结构和动态模拟.
- 使用X射线分析,动态核磁共振 (NMR) 谱学和紫外线谱学进行实验验验证.
主要成果:
- 计算的结构和动态模式与实验观察结果准确匹配.
- 确定了围绕C-N单键环绕旋转的低屏障.
- 确定了微不足道的n-π结合和高的反转障碍.
- 证实了原子的高金字塔性.
结论:
- 这项研究提供了对N,N-bis(silyloxy) enamine立体动力学的全面了解.
- 独特的结构特征,包括金字塔性,解释了观察到的高反应性.
- DFT模拟作为一种可靠的工具,用于预测新型胺类的行为.
相关概念视频
VSEPR Theory and the Effect of Lone Pairs
Effect of Lone Pairs of Electrons on Molecule Geometry
Newman Projections
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
Chirality at Nitrogen, Phosphorus, and Sulfur
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
Molecular Structure and Acidity
An acid can be deprotonated to form a conjugate base or an anion. If the produced anion is more stable, then the acid is stronger. On the contrary, if the anion is unstable, then the acid is weaker. Hence, to determine the acidity of the compound, the stability of its conjugate base is studied using various factors.
The size effect explains the change in atomic size on acidity. When comparing the acids formed from elements that belong to the same column in the periodic table, their atomic sizes...
The size effect explains the change in atomic size on acidity. When comparing the acids formed from elements that belong to the same column in the periodic table, their atomic sizes...
Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...


