ジルコニウムサリチロキサゾリンの複合体による触媒性サイクロヒドロアミネーションのメカニズム
Laura E N Allan1, Guy J Clarkson, David J Fox
1Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV7 4AL, UK.
Journal of the American Chemical Society
|October 14, 2010
まとめ
本研究では,ジルコニウム触媒を用いた水素アミネーション/サイクリングメカニズムを調査しています. 重要な発見は,環閉ではなく,N-H結合破裂が反応速度を決定し,反応性イミド種形成を提案することです.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- 反応メカニズム 解明 解明
背景:
- 窒素を含む化合物の合成には,ヒドロアミネーション/サイクリング反応が不可欠である.
- ジルコニウムベースの触媒は,有機変換においてユニークな反応性プロファイルを提供します.
- 反応メカニズムの理解は,触媒の設計と最適化に不可欠です.
研究 の 目的:
- Cp * LZr (((NMe (((2)) ((2)) 複合体によって触媒化された水素アミネーション/サイクル化の詳細なメカニズムを解明する.
- 速度決定ステップ (RDS) と,触媒サイクルに含まれる主要な中間物質を特定する.
- 反応速度と経路に対する触媒構造と反応条件の影響を調査する.
主な方法:
- 速度法則とアクティベーションパラメータを決定するための運動学的研究.
- 中間物質を特徴付けるためのステイキオメトリックおよびインシットNMRスペクトロスコピック研究.
- 触媒構造とステリック効果を分析するためのX線結晶学.
主要な成果:
- 速度法則 d[基質]/dt = k[触媒](1) [基質](0) は,触媒に依存し,基質に依存しない速度決定のステップを示しています.
- 有意な運動同位体効果 (KIE) は,リングの閉塞に先行するRDSとしてN-H結合破裂を指しています.
- 触媒の固体質量の増加は反応速度を高め,反応後にはC-H活性化による触媒のメタラサイクリック種への変換が起こります.
結論:
- このメカニズムは,アミドメカニズムを除いて,反応性イミド種の速度決定的形成を伴う.
- 金属中心はRDSでルイス酸として作用しませんが,活性化基板が関与しています.
- 触媒サイクルが提案され,C-H活性化による触媒の無効化で頂点に達します.
関連する概念動画
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