硫酸フェノール,ベンジルアルコール,アニリンのパラセレクティブ,イリジウム触媒C-Hボリレーション,イオン対の静電相互作用によって導かれる
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PubMedで要約を見る
まとめ
この要約は機械生成です。塩のパラC−Hボリレーションは,イリジウム触媒を用いて達成された. 選択性はカチオンアルキル鎖長とリガンド置換剤によって制御され,特定のリガンドはイオンペアリング効果によってパラ選択性を強化した.
科学分野
- 有機金属化学
- キャタリシス
- 合成有機化学
背景
- C-Hボリレーション (CHB) は,C-C結合形成の重要な変換である.
- アムニウム塩のような挑戦的な基板のための選択的CHB反応の開発は,活発な研究分野です.
- イリジウム触媒は,様々なC-H機能化反応に有効である.
研究 の 目的
- テトラアルキルアモニウム硫酸塩と硫酸塩のパラC-Hボリレーションを達成する.
- 触媒構造と基板特性の選択性への影響を調査する.
- これらの反応におけるパラ選択性を支配するメカニズムを解明する.
主な方法
- C-H ボリル化のためにバイピリジン結合のイリジウムボリル触媒を使用した.
- テトラアルキルアモニウムカチオンのアルキル鎖の長さを体系的に変化させた.
- ビピリジンのリガンドの変形代用剤
- 選択性を決定するために反応製品を分析した.
主要な成果
- テトラアルキルアモニウム硫酸塩と硫酸塩のパラC-Hボリレーションが成功しました.
- 選択性は,カチオンアルキル群長とビピリジンリガンド置換剤の両方によって調節されることが示された.
- 4,4'-ジメトキシ-2,2'-ビピリジンは,優れた選択性を提供するリガンドとして特定されました.
- カチオンアルキル群がメタC-H結合を遮断し,ボリレーションをパラ位置に導いたイオンペアリングメカニズムを提案した.
結論
- テトラアルキラムニウム塩のパラC-Hボリレーションは,Ir触媒を用いて実行可能である.
- 触媒の設計 (リガンドの選択) と基板構造 (カタニンアルキル鎖) は,選択性を制御する上で極めて重要です.
- イオンペアリングはパラ選択性を指向する上で重要な役割を果たし,標的型機能化の経路を提供します.
関連する概念動画
Overview
Alcohols are one of the most important functional groups in organic chemistry. The name of alcohol comes from the hydrocarbon from which it is derived. Alcohols are organic molecules containing the functional hydroxyl or –OH group directly bonded to carbon. Phenols have an OH group directly attached to a benzene ring. While alcohols are colorless, phenol is a white crystalline compound with a characteristic "hospital smell" odor.
As with other organic compounds, alcohols and...
Alcohols are organic compounds in which a hydroxy group is attached to a saturated carbon. Phenols are a class of alcohols containing a hydroxy group attached to an aromatic ring. The physical properties of the alcohols and phenols are influenced by hydrogen bonding due to the oxygen–hydrogen dipole in the hydroxy functional group and dispersion forces between alkyl or aryl regions of alcohol and phenol molecules.
Alcohols possess a higher boiling point than aliphatic hydrocarbons of similar...
Ortho–para directors are substituent groups attached to the benzene ring and direct the addition of an electrophile to the positions ortho or para to the substituent. All electron-donating groups are considered ortho–para directors. They donate electrons to the ring and make the ring more electron-rich. The ring is therefore susceptible to the addition of electrophiles. Substituents such as amino, hydroxy, or alkoxy, containing lone pairs on the atom adjacent to the ring, donate...
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...
Like water, alcohols are weak acids and bases. This is attributed to the polarization of the O–H bond making the hydrogen partially positive. Moreover, the electron pairs on the oxygen atom of alcohol make it both basic and nucleophilic. Protonation of an alcohol converts hydroxide, a poor leaving group, into water—a good one. The two acid–base equilibria corresponding to ethanol are depicted below.
Figure 1. Loss of proton
Figure 2. Gain of proton
Methanol (pKa = 15.5) is the only...
In a dehydration reaction, a hydroxyl group in an alcohol is eliminated along with the hydrogen from an adjacent carbon. Here, the products are an alkene and a molecule of water. Dehydration of alcohols is generally achieved by heating in the presence of an acid catalyst. While the dehydration of primary alcohols requires high temperatures and acid concentrations, secondary and tertiary alcohols can lose a water molecule under relatively mild conditions.
The acid-catalyzed dehydration of...