キラルルイス酸によって触媒化された2-ベンゾピリウム-4-オラートの高度なエナンチオセレクティブの1,3-二極サイクロアディション反応
Hiroyuki Suga1, Kei Inoue, Shuichi Inoue
1Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380-8553, Japan. sugahio@gipwc.shinshu-u.ac.jp
Journal of the American Chemical Society
|December 12, 2002
まとめ
チラル・ルイス酸触媒,特に2,6-bis(oxazolinyl) ピリジン (Pybox) を含んだ希土金属トリフラート複合体は,2-ベンゾピリウム-4-オラートの高度にエナチオセレクティブの1,3-二極サイクロアディションを可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・カタリシス
背景:
- 1,3-二極サイクロアディション反応は,ヘテロサイクリック化合物の合成に不可欠です.
- これらの反応において高いエナチオ選択性を達成することは,キラル分子の生成に不可欠である.
研究 の 目的:
- ルイス酸の触媒として,キラル 2,6-bis(oxazolinyl) ピリジン (Pybox) - 稀土金属トリフラート複合体の使用を調査する.
- 2-ベンゾピリウム-4-オラトの1,3-二極サイクロアディションで有意なエナンチオセレクティブ性を達成するために.
主な方法:
- ルイス酸の触媒としてキラル型パイボックス・レアアース金属トリフラート複合体を利用した.
- ベンジロキシアセタルデヒド誘導体,ベンジルピルバート,3-アクリロイル-2-オクサゾリジドンを含む様々な基板で1,3-二極サイクロアディション反応を行った.
- 異なるPyboxリガンド (i-PrとPh) を含むスカンジウム (Sc(III)) とイテルビウム (Yb(III)) ベースの触媒を使用しています.
主要な成果:
- Sc(III) -Pybox-i-Prを触媒化した反応は,最大93%のエナティオメール過剰 (ee) を有するエンドアダクトを生成した.
- ベンジルピルバートとの反応により,e.e.の87%のエクソアダクトが得られました.
- Yb(III) -Pybox-Phは,3-アクリロイル-2-オクサゾリディノンとの反応を効果的に触媒化し,98%のEEを持つエクソアダクトを生成しました.
結論:
- チラル・パイボックス・レアアース・メタル・トリフラート・コンプレックスは,エナチオセレクティブの1,3-二極サイクロアディションの効果的な触媒である.
- 金属とPyboxリガンドの選択は,反応のステレオ化学的結果 (エンド/エクソ) とエナチオ選択性に影響します.
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