アミドを軽度な条件下でアルコールとアミンに直接水素化する
Ekambaram Balaraman1, Boopathy Gnanaprakasam, Linda J W Shimon
1Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel.
Journal of the American Chemical Society
|November 6, 2010
まとめ
新しい触媒的方法では,C-N結合割れによって,アミドをアルコールとアミンに直接変換する. この選択的水素化は,温和な条件下でルテニウムピンチャー複合体を使用し,効率的でグリーンな変換を提供します.
科学分野:
- カタリシス カタリシス カタリシス
- 有機化学 オーガニック・ケミストリー
- グリーン・ケミストリー (Green Chemistry)
背景:
- アミド機能群の変換は,有機合成において極めて重要です.
- アミド還元のための既存の方法は,しばしば厳しい条件またはステキオメトリック反応剤を必要とします.
- アミドにおけるC-N結合の選択的な割れ方は,合成上の課題である.
研究 の 目的:
- アミドの直接水素化のための新しい触媒システムを開発する.
- C-N結合の選択的な割れ方を達成し,アルコールとアミンを生成します.
- この変換のメカニズムとその適用性を探求する.
主な方法:
- ホモゲーヌスな触媒として,二ピリジル基のPNN Ru(II) ピンチャー複合体を使用した.
- 軽圧と中性条件下で水素化反応を行った.
- 金属-リガンドの協力とピンサーコアの芳香化-脱芳香化を含む反応機構を調査した.
主要な成果:
- アミドをアルコールとアミンに選択的に直接水素化し,C-N結合の割れ方を達成した.
- 観察された最小のC-O割れ分産物,アニリドの微量を除く.
- アミド基板の範囲で良好から優れた収量を示しています.
- 触媒プロセスは,環境に優しい環境下で動作します.
結論:
- アミド水素化のための新しい効率的な触媒システムが確立されました.
- 開発された方法は,アミドからアルコールとアミンを合成するためのグリーンで直接的な経路を提供します.
- 機械学的洞察は,触媒サイクルにおける金属-リガンドの協力の役割を強調しています.
関連する概念動画
01:07Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
02:13Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
01:28Amides to Carboxylic Acids: Hydrolysis
Amides can undergo either acid-catalyzed hydrolysis or base-promoted hydrolysis through a typical nucleophilic acyl substitution. Each hydrolysis requires severe conditions.
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
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.
01:20Amides to Amines: LiAlH4 Reduction
Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.