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相关概念视频

Crown Ethers02:36

Crown Ethers

5.4K
Crown ethers are cyclic polyethers that contain multiple oxygen atoms, usually arranged in a regular pattern. The first crown ether was synthesized by Charles Pederson while working at DuPont in 1967. For this work, Pedersen was co-awarded the 1987 Nobel Prize in Chemistry. Crown ethers are named using the formula x-crown-y, where x is the total number of atoms in the ring and y is the number of ether oxygen atoms. The term 'crown' refers to the crown-like shape that these ether...
5.4K
Thermal and Photochemical Electrocyclic Reactions: Overview01:26

Thermal and Photochemical Electrocyclic Reactions: Overview

2.4K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.4K
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)01:16

Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)

2.7K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
2.7K
Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

2.1K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.1K
Chair Conformation of Cyclohexane02:02

Chair Conformation of Cyclohexane

15.2K
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
15.2K
Photochemical Electrocyclic Reactions: Stereochemistry01:26

Photochemical Electrocyclic Reactions: Stereochemistry

1.9K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
1.9K

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相关实验视频

Updated: Sep 12, 2025

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation
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Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

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皇冠乙- 罗塔克桑酸.

Peng-Lai Wang1,2, Peng Chen1, Raorao Yang1

  • 1School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, P.R. China.

Angewandte Chemie (International ed. in English)
|August 6, 2025
PubMed
概括

我们开发了一种无金属的方法来合成皇冠乙烯罗塔克桑. 这种技术允许对链进行控制的皇冠以太放置,从而创建受保护和稳定的机械互锁分子.

关键词:
活跃模板合成 活跃模板合成拉索酸是一种拉索酸.机械上相互锁定的分子.罗塔克桑酸是一种罗塔克桑酸.

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Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly
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Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

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相关实验视频

Last Updated: Sep 12, 2025

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation
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Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

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Constructing Cyclic Peptides Using an On-Tether Sulfonium Center
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Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly
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科学领域:

  • 超分子化学 超分子化学
  • 有机合成 有机合成
  • 化学生物学 化学生物学

背景情况:

  • 机械互锁分子 (MIMs) 具有独特的结构和功能特性.
  • 基于的MIM对仿生应用有兴趣.
  • 基于的MIM的受控合成仍然是一个挑战.

研究的目的:

  • 报告皇冠乙烯罗塔克桑的无金属活性模板合成.
  • 为了证明位置异构体的选择性合成和表征.
  • 为了研究宏观循环线程的形状和稳定性影响.

主要方法:

  • 使用24-皇冠-8宏循环和甘氨酸残留物的活性模板合成.
  • 从N和C末端选择性延伸轴.
  • 通过1H核磁共振光谱学和双重质谱学进行结构确认.

主要成果:

  • 成功合成了三种不同的位置异构体的七个 [2]rotaxanes.
  • 在轴上确认了独特的宏循环放置.
  • 与线性相比,观察到罗塔克桑的改变形状,化学稳定性和二次相互作用.
  • 证明了残留物对酶降解的局部保护.

结论:

  • 开发的策略使皇冠乙烯罗塔克桑的无金属合成成为可能.
  • 定位异构影响着罗塔xane 构造和稳定性.
  • 皇冠以太线程提供局部化的酶保护,为新的类同类物铺平了道路.