ニッケルで触媒化された分子間 [2 + 2] サイクル添加で,アルケネと結合したエニンがアルケネと結合する
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
まとめ
新しいニッケル触媒によるサイクロアディション反応は,結合されたエニンとアルケーンからサイクロブテン環を効率的に生成します. この方法は,副作用を回避し,選択性のために重要なブタディエニル調整を使用します.
科学分野:
- 有機金属化学 有機金属化学
- オーガニック・シンセシス オーガニック・シンセシス
- カタリシス カタリシス カタリシス
背景:
- 分子間 [2+2] サイクロアディションは,四つ組のリングを形成するために不可欠です.
- サイクロアディションのための選択的で効率的な触媒方法の開発は,依然として課題です.
- ニッケル触媒は,新しい有機変異のための多用途のプラットフォームを提供します.
研究 の 目的:
- 新しいニッケル触媒による分子間 [2+2]サイクル添加反応の開発.
- 様々なアルケンと結合エニンとの反応の範囲と限界を探求する.
- そのメカニズム,特に選択性の達成における中間複合体の役割を解明する.
主な方法:
- 結合エニンとアルケンのニッケル触媒反応.
- 反応条件と触媒のスクリーニング.
- 反応中間物質の分離と特徴付け.
- 調整モードを決定するスペクトロスコピク分析.
主要な成果:
- ニッケル触媒による分子間 [2+2]サイクル添加の成功開発.
- 電子欠乏性アルケーンやノルボネンや1デセネンなどの中性アルケーンを含む幅広い基板範囲.
- 結合エニンは,オリゴメリゼーションやサイクロトリメリゼーションなどの副作用を効果的に抑制しました.
- 中間複合体の分離は,選択的なサイクロブテンの形成の鍵として η(3) -ブタディエニル協調性を確認しました.
結論:
- 開発されたニッケル触媒反応は,サイクロブテンのための効率的な経路を提供します.
- 結合エニンの使用は反応選択性を高め,望ましくない副産物を防止します.
- η(3) -ブタジエニル調整の役割を理解することは,将来の触媒システムの設計に不可欠です.
関連する概念動画
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.