アモニアとリチウムアミドのパラジウム触媒結合とアリルハリドの結合
1Department of Chemistry, Yale University, Post Office Box 208107, New Haven, Connecticut 06520-8107, USA.
Journal of the American Chemical Society
|August 3, 2006
まとめ
新しいパラジウム触媒結合法により,アリルハライドとアンモニアから一次アリラミンが効率的に生成されます. この反応は高い選択性を示し,ダイアリアミンの形成を最小限に抑え,新しいオルガンパラジウム複合体の分離を可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
- 有機金属化学 有機金属化学
背景:
- パラジウムによって触媒化されたクロスカップリング反応は,有機合成において不可欠である.
- プライマリアライアミンの効率的な合成は依然として課題です.
- アミネーション反応における選択性の制御は極めて重要です.
研究 の 目的:
- 主要アリラミン合成のための軽度かつ選択的なパラジウム触媒法を開発する.
- このプロセスにおけるオルガノパラジウム中間物質の形成を調査する.
主な方法:
- アリルハリドとアンモニアまたはリチウムアミドをパラジウム触媒を用いて結合する.
- オーガノパラジウム複合体の分離と特徴付け.
- 製品比率による反応選択性の分析.
主要な成果:
- アリルハライドとアンモニア/リチウムアミドの軽度な,パラジウム触媒による結合が達成された.
- 主要な製品として形成されたプライマリアライラミンは,高い選択性 (9.5:1から>50:1アライラミン:ダイアリラミン) を有していた.
- 末端 -NH2 リガンドを特徴とする最初のオルガンパラジウム複合体を分離し,リダクティブに除去してアリラミンを生成します.
結論:
- 開発された方法は,一次アリラミンへの効率的な経路を提供します.
- この高い選択性は,既存のアミネーション方法に比べて優位性があります.
- 孤立したオルガノパラジウム複合体は,アリラミン形成に関するメカニズム的な洞察を提供します.
関連する概念動画
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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...
Amides 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.
Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
Preparation of Amines: Alkylation of Ammonia and Amines
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
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Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
Preparation of Amines: Reduction of Amides and Nitriles
Nitriles can be reduced to primary amines using reducing agents like lithium aluminum hydride or catalytic hydrogenation. The reduction introduces an amino group with an extra carbon in the skeleton. Nitriles are formed from the reaction between alkyl halides and sodium cyanide through the SN2 mechanism. Primary alkyl halides are the preferred substrates to prepare nitriles.
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
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