1,2-アザボリンの独特の電子構造は,解像度化学を介して2つの新しいレジオアイソメリックビルディングブロックを解き放つ
Cameron R McConnell1, Fredrik Haeffner1, Andrew W Baggett1
1Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02467 , United States.
Journal of the American Chemical Society
|May 15, 2019
まとめ
新しい1,2-アザボリンの構成要素は,C4とC5の位置での多様化を可能にします. 研究者は,これらの重要なヘテロサイクルの混合物を区別して,C4-またはC5-ボリル化異体と選択的に反応する方法を開発した.
科学分野:
- 有機化学
- ヘテロサイクル化学
- 合成方法論
背景:
- 1,2-アザボリンは独特の電子特性を持つヘテロサイクル化合物である.
- 1,2-アザボリン,特にC4およびC5における特定のリング位置の機能化は困難であった.
- 合成用途では,異なる位置に置換素を持つ同位体間の区別が不可欠である.
研究 の 目的:
- C4 と C5 の位置を多様化するための新しい1,2-アザボリン構成要素を開発する.
- C4-およびC5-ボリレイテッド 1,2-アザボリンの電子構造と反応性を調査する.
- C4 と C5 のボリル化同位体混合物を選択的に区別する方法を確立する.
主な方法:
- 新しい1,2-アザボリン構成要素の合成
- 反応性研究と運動測定
- 密度関数理論 (DFT) の計算
- 選択的酸化,イリジウム触媒によるデボリレーション,およびリガンド交換反応.
主要な成果:
- C4とC5の多様化のための1,2-アザボリン構成要素の開発に成功した.
- C4-およびC5-ボリレイテッド1,2-アザボリンの混合物の分解は,それらの独特の電子構造によって可能である.
- 選択的酸化 (NMO) のC4-ボリル化および選択的Ir-触媒化デボリレーションのC5-ボリル化同位体 (運動制御) の実証
- C4-ボリル化同位体に対するダイエタノアミンとの選択的リガンド交換 (熱力学的制御).
結論:
- この研究は,2つのアリル単一-Bピン置換異性体の混合物を化学的に区別する最初の例を提供します.
- C4とC5の位置の異なる電子構造は,それらの異なる反応性を決定する.
- これらの発見は1,2-アザボリンヘテロサイクルの広範な多様化のための貴重な合成ツールを提供します.
関連する概念動画
02:34Structural Isomerism
16.8K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly,...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly,...
16.8K
01:33Regioselective Formation of Enolates
2.6K
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are more stable. But the energy required to form kinetic enolates is less.
2.6K
01:19Structure of Amines
2.5K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’...
2.5K
01:22Preparation of 1° Amines: Azide Synthesis
2.6K
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
2.6K
01:26Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism
2.1K
The Hofmann and Curtius rearrangement reactions can be applied to synthesize primary amines from carboxylic acid derivatives such as amides and acyl azides. In the Hofmann rearrangement, a primary amide undergoes deprotonation in the presence of a base, followed by halogenation to generate an N-haloamide. A second proton abstraction produces a stabilized anionic species, which rearranges to an isocyanate intermediate via an alkyl group migration from the carbonyl carbon to the neighboring...
2.1K
01:371° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
3.3K
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
3.3K