解決されたキラル3,4-ディアザフォスフォランおよびその応用が,触媒的非対称性アリルアルキル化に用いられる
Thomas P Clark1, Clark R Landis
1Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|September 25, 2003
まとめ
研究者らは,触媒的応用のために新しいキラル・フォスフィンを開発した. これらの新種の化合物は,パラジアム触媒によるアリルアルキル化反応において高いエナチオセレクティブ性を示し,非対称合成の有望性を示しています.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・カタリシス
- オーガノフォスファルス 化学 化学
背景:
- キラル・フォスフィンは,非対称な触媒の重要なリガンドであり,エナティオメリカルに純粋な化合物の合成を可能にします.
- 新規のキラル・フォスフィン・リガンドへの効率的な合成経路の開発は,触媒的方法論の進歩に不可欠である.
- パラジウム触媒によるアリルアルキレーションは,炭素-炭素結合形成のための強力なツールであり,エナチオセレクティブ性のためにしばしばキラルリガンドを必要とします.
研究 の 目的:
- 新種のキラル・フォスフィン・リガンドを合成する.
- パラジウム触媒による非対称アリルアルキル化におけるこれらのリガンドの有用性を調査する.
- リンガンド構造と反応条件がエナチオセレクティビティに及ぼす影響を調査する.
主な方法:
- ラセミク・フォスフィンの前駆体を合成するためのワンポット凝縮反応.
- ダイアステロエーマー塩の結晶化によるラセミク混合物の分解.
- 溶解したフォスフィンとアミノ酸とアミンの結合により,キラルリガンドライブラリが生成されます.
- 合成されたキラルフォスフィンを用いたパラジアム触媒による非対称性アリルアルキレーション.
主要な成果:
- 新しいフォスフィンであるrac-N,N'-phthaloyl-2,3-(2-carboxyphenyl) -phenyl-3,4-diazaphospholane (rac-2) は,88%の収穫率で合成されました.
- チラル・フォスフィン (3) は,解像度およびその後の派生化によってアクセスされました.
- 高いエナチオ選択性 (最大97% ee) は,アリルアセテートのパラジウム触媒によるアリルアルキル化で得られた.
- アミノ酸置換剤に対するエナンチオセレクティビティの有意な感受性およびPF6-塩の存在が観察されました.
結論:
- 多様なキラル・フォスフィン・リガンドを合成するための新しい効率的な方法が確立されました.
- 合成されたキラルフォスフィンは,パラジアム触媒による非対称性アリルアルキル化のための効果的なリガンドである.
- リガンドの設計,特にアミノ酸付属体と対付属体は,高いエナチオセレクティビティを達成する上で重要な役割を果たします.
関連する概念動画
01:01Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
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01:07Acid Halides to Amides: Aminolysis
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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...
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01:19Acid Halides to Alcohols: LiAlH4 Reduction
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The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
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