非対称的な還元アルドール反応におけるRh (Phebox) 触媒の高性能:高反選択性
Hisao Nishiyama1, Takushi Shiomi, Yasunori Tsuchiya
1Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan. hnishi@apchem.nagoya-u.ac.jp
Journal of the American Chemical Society
|May 12, 2005
まとめ
チラルロジウム触媒は,効率的な非対称的還元アルドール反応を可能にします. このプロセスは,高い抗およびエナチオ選択性を持つβ-ヒドロキシプロピオネートを生成し,おそらく周期的な移行状態を経由します.
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
- アシンメトリック・シンセシス
背景:
- 非対称的還元性アルドール反応は,キラル分子合成に不可欠である.
- この変換のための効率的な触媒システムの開発は,有機化学における重要な課題です.
研究 の 目的:
- 非対称的な還元性アルドール反応のための高度に選択的な触媒システムを開発する.
- 反応のメカニズムとステレオ化学的結果を調査する.
主な方法:
- キラルロジウム (((ビソキサゾリニルフェニル) 複合体を触媒 (1モル%) として利用した.
- 様々なアルデヒド,アルファ,ベータ不飽和エステル,および水素シランを基質として使用した.
- 50°Cで0.5-1.0時間,反応を行った.
主要な成果:
- 非対称的還元性アルドール反応の効率的な触媒が達成されました.
- 得られたβ-ヒドロキシプロピオネートは,優れた抗選択性 (最大98%) とエナチオ選択性 (最大96% ee) を有する.
- ステレオ化学的結果を説明するために,ロジウム- ((E)) -エノラート中間体を含む椅子のような周期的な移行状態を提案した.
結論:
- チラルロジウム ((ビソザゾリニルフェニル) 複合体は,非対称的還元アルドール反応の非常に効果的な触媒である.
- 開発された方法は,エナチオメリックに濃縮されたβ-ヒドロキシプロピオネートへの簡単な経路を提供します.
- 提案された移行状態モデルは,観測された高いステレオ選択性を合理化します.
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