JoVE - Journal of Visualized Experiments
JoVE Visualize
Contact Us
这页已由机器翻译。其他页面可能仍然显示为英文。 View in English

光催化 [4 + 1] 循环添加 获取多替代的2-氨基-2,5-二

  • 0School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, P. R. China.
Organic Letters +

|

2025年九月1日

在PubMed上查看摘要

概括

此摘要是机器生成的。

相关概念视频

Cycloaddition Reactions: Overview 01:16

2.8K

Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.

The feasibility of cycloaddition reactions under thermal and photochemical conditions can be...

Cycloaddition Reactions: MO Requirements for Photochemical Activation 01:12

2.2K

Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.

Thermally-induced [2 + 2] cycloadditions are symmetry forbidden. This is because the ground state HOMO of one ethylene molecule and the LUMO of the other ethylene are out of phase, preventing a concerted suprafacial-suprafacial overlap.
Absorption...

Cycloaddition Reactions: MO Requirements for Thermal Activation 01:16

3.7K

Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.

The reaction occurs between the highest occupied molecular orbital (HOMO) of one π component and the lowest unoccupied molecular orbital (LUMO) of the other. These are...

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction 01:16

10.5K

The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.

From a molecular orbital perspective, the interacting lobes of the two π systems must be in phase...

Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation 01:27

2.3K

Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).

The ring-forming reaction occurs in two stages: Michael addition and the subsequent...

Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene 01:13

6.4K

Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.

Unlike fluorine, iodine is highly unreactive for...