Jove
Visualize
联系我们
JoVE
x logofacebook logolinkedin logoyoutube logo
关于 JoVE
概览领导团队博客JoVE 帮助中心
作者
出版流程编辑委员会范围与政策同行评审常见问题投稿
图书馆员
用户评价订阅访问资源图书馆顾问委员会常见问题
研究
JoVE JournalMethods CollectionsJoVE Encyclopedia of Experiments存档
教育
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab Manual教师资源中心教师网站
使用条款与条件
隐私政策
政策

相关概念视频

Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

2.0K
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.
2.0K
Pericyclic Reactions: Introduction01:17

Pericyclic Reactions: Introduction

8.3K
Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
8.3K
Thermal and Photochemical Electrocyclic Reactions: Overview01:26

Thermal and Photochemical Electrocyclic Reactions: Overview

2.3K
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.
2.3K
Photochemical Electrocyclic Reactions: Stereochemistry01:26

Photochemical Electrocyclic Reactions: Stereochemistry

1.8K
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
1.8K
Woodward–Hoffmann Selection Rules and Microscopic Reversibility01:34

Woodward–Hoffmann Selection Rules and Microscopic Reversibility

3.1K
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
3.1K
Cycloaddition Reactions: Overview01:16

Cycloaddition Reactions: Overview

2.6K
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.
2.6K

您也可能阅读

相关文章

通过共同作者、期刊和引用图与本文相关的文章。

排序
Same author

Enhancing Isoprenol Phosphorylation Through Combined Engineering of Mevalonate Kinase.

Chembiochem : a European journal of chemical biology·2026
Same author

Exploring bacterial cytochrome P450s for selective activation of aliphatic C-H bonds in pentacyclic triterpenoids.

Nature chemistry·2026
Same author

Discovery and engineering of bacterial P450s for C-14 hydroxylation in ent-kaurane diterpenoids.

Nature communications·2026
Same author

A Single Residue Switch Controls Isomer Selectivity in the Myxobacterial Isobonnadiene Synthase.

Organic letters·2026
Same author

Engineering class I terpene synthases for skeletal diversity: strategies and applications.

Natural product reports·2025
Same author

Discovery and Characterization of a <i>cis</i>-Casbene Diterpene Synthase from <i>Streptomyces paromomycinus</i>.

Journal of natural products·2025

相关实验视频

Updated: Jul 8, 2025

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products
07:59

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products

Published on: October 4, 2019

9.8K

二等级的烯循环:结构,机制和工程.

Xingming Pan1, Jeffrey D Rudolf2, Liao-Bin Dong1

  • 1State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 211198, China. ldong@cpu.edu.cn.

Natural product reports
|December 18, 2023
PubMed
概括

第二类烯循环酶 (TCs) 启动复杂的天然产品生物合成. 了解它们的机制是酶工程和创造新 terpenoids 的关键.

科学领域:

  • 生物化学 生物化学
  • 自然产品生物合成 自然产品生物合成
  • 酵素工程是什么意思 酵素工程

背景情况:

  • 烯循环酶 (TCs) 是关键的酶,负责合成已知超过95,000种类天然产物.
  • 规范性TC根据结构,功能和反应机制被分为两种类型.
  • 第二类TC单独调解各种异oprenoid基质的酸启动的循环反应.

研究的目的:

  • 审查在自然界中发现的多样化的II类烯环酸.
  • 探索它们在重要自然产品如植物激素和真菌美类物质的生物合成中的作用.
  • 突出它们在酶工程中的潜力,以发现新型分子.

主要方法:

  • 在2023年7月之前对II类TC进行全面的文献审查.
  • 对各种II类TC的序列,结构和反应机制的分析.
  • 检查结构引导的工程研究.

主要成果:

  • 在生物活性化合物的早期生物合成步骤中,II类TC至关重要.
  • 这些酶在产生吉伯雷林和真菌美洛特类物质方面起着重要作用.
  • 它们的催化机制和生物催化潜力具有重大意义.

更多相关视频

Transient Expression in Nicotiana Benthamiana Leaves for Triterpene Production at a Preparative Scale
08:56

Transient Expression in Nicotiana Benthamiana Leaves for Triterpene Production at a Preparative Scale

Published on: August 16, 2018

17.3K
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
09:42

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

9.0K

相关实验视频

Last Updated: Jul 8, 2025

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products
07:59

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products

Published on: October 4, 2019

9.8K
Transient Expression in Nicotiana Benthamiana Leaves for Triterpene Production at a Preparative Scale
08:56

Transient Expression in Nicotiana Benthamiana Leaves for Triterpene Production at a Preparative Scale

Published on: August 16, 2018

17.3K
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
09:42

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

9.0K

结论:

  • 对II类TC的彻底理解对于扩大类结构多样性至关重要.
  • 工程II类TC为创造新型生物活性分子提供了令人兴奋的前景.
  • 对它们机制的进一步研究将推动生物合成和有机化学方面的创新.