催化分子间 [2 + 2] 循环添加与基因结合的酶
Akira Nishimura1, Masato Ohashi, Sensuke Ogoshi
1Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
Journal of the American Chemical Society
|September 13, 2012
概括
一个新的催化循环添加反应有效地从结合的和中创建循环丁环. 这种方法避免了副作用,并利用一个关键的butadienyl协调选择性.
科学领域:
- 有机金属化学 有机金属化学
- 有机合成 有机合成
- 催化剂是一种催化剂.
背景情况:
- 分子间 [2+2] 循环添加对于形成四个成员的环来说至关重要.
- 为循环添加开发选择性和高效的催化方法仍然是一个挑战.
- 催化为新型有机转化提供了一个多功能平台.
研究的目的:
- 开发一种新的催化分子间 [2+2] 循环添加反应.
- 探索与各种基和合酶反应的范围和局限性.
- 阐明机制,特别是中间复合体在实现选择性方面的作用.
主要方法:
- 催化反应的结合与.
- 对反应条件和催化剂的选.
- 反应中间体的分离和表征.
- 谱分析以确定协调模式.
主要成果:
- 催化分子间 [2+2] 循环添加的成功开发.
- 广泛的基质范围包括缺电子的基和中性基,如norbornene和1-decene.
- 结合酶有效抑制了诸如寡聚化和循环三聚化之类的副作用.
- 通过分离中间复合物,证实了 η(3) - - 丁基协调是选择性环丁烯形成的关键.
结论:
- 开发的催化反应提供了一个有效的循环丁的途径.
- 结合酶的使用增强了反应选择性,并防止了不必要的副作用.
- 对于设计未来的催化系统来说,了解 η(3) - - 丁协调的作用至关重要.
相关概念视频
01:16Cycloaddition Reactions: Overview
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.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
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.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
01:14Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.