ビノルのピロボラート,スピロボラート,ボロキシナート - 組立,構造,反応性
Gang Hu1, Anil K Gupta1, Li Huang1
1Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Journal of the American Chemical Society
|June 29, 2017
まとめ
この研究では,BINOLのリガンドは,ボロキシナートとスピロボラートを含む様々なボラート種を形成し,効果的な非対称な触媒として作用することが明らかになった. 3,3′-Ph2BINOLのような特定のBINOL誘導体は,アジリジネーション反応において優れた触媒性能を呈する.
科学分野:
- 有機金属化学
- 非対称な触媒
- ボロン化学
背景:
- VANOLとVAPOLのリガンドは,B ((OPh)) 3で効果的なボロキシナート触媒を形成する.
- BINOLのリガンドは,VANOL/VAPOLとは異なり,B ((OPh) 3で弱い触媒であることが以前発見されました.
- BINOLのボラートエステルは,メソボラートやスピロボラートなどの様々な形態で存在する,知られているキラル触媒です.
研究 の 目的:
- B (OPh) 3のステキオメトリーによって形成されるビノール由来ボラートエステルの構造を調査する.
- これらのBINOLボラート種の触媒活性と非対称的誘導を評価する.
- 異なるBINOL誘導体と反応条件が触媒種の形成にどのように影響するかを理解する.
主な方法:
- BINOLとB ((OPh)) の異なるモラ比を用いたBINOLボラートエステルの合成
- 形成されたボラート種 (ピロボラート,スピロボラート,ボロキシナート) の構造的特徴
- 非対称なアジリディネーション反応における触媒性能の評価
主要な成果:
- BINOLは,これまで考えられていたとは異なり,ボロキシナートとスピロボラート種を形成することができる.
- これらのBINOLボラート種は,時には反対の非対称的誘導で,触媒的活性を示すことができます.
- 3,3'-非置換されたBINOL誘導体,特に3,3'-Ph2BINOLは,非対称なアジリディネーションのための効果的なボロキシナート触媒を形成する.
結論:
- BINOL由来ボラート種は本質的に劣った触媒ではない.その構造と性能は反応条件とリガンド置換に依存する.
- 特定のボラート構造 (ボロキシナート,スピロボラート) の形成が触媒的結果を決定する.
- 置換されたBINOLリガンドは,調整可能な触媒特性を提供し,3,3'-位置でステリカルに要求されるグループは,触媒形成を阻害する可能性があります.
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