オーガノプラチナム (II) エノラート複合物からβ-水素の除去のメカニズム的研究
Erik J Alexanian1, John F Hartwig
1Department of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Journal of the American Chemical Society
|October 29, 2008
まとめ
この研究では,プラチナ(II) エノラート複合体を調査し,β-水素の除去が熱分解の鍵であり,メタンとエノンを形成することを明らかにしました. 反応速度は,フォスフィン濃度とエノラート置換物の影響を受けます.
科学分野:
- 有機金属化学 有機金属化学
- 反応メカニズム 反応メカニズム
- プラチナ・カタリシス
背景:
- ビスホスフィンアルキルプラチナ (II) エノラート複合体は,有機金属反応における重要な中間物質である.
- それらの熱分解経路を理解することは,新しい触媒プロセスを設計するために不可欠です.
研究 の 目的:
- ビスフォシンアルキルプラチナ (II) エノラート複合体における熱反応の詳細なメカニズム的経路を解明する.
- エノラートとアルキルプラチナ複合体におけるβ-水素除去のメカニズムと運動を比較する.
主な方法:
- 熱反応の詳細なメカニズム調査.
- 反応速度の依存性を判定するための運動学的研究.
- 速度を制限するステップを特定するための運動同位体効果測定.
- ステリックおよび電子効果を評価するために,置換されたエノラート複合体に関する研究.
主要な成果:
- 熱反応によりメタンとエノンが生成され,その分子の分布はエノンのステリックに依存する.
- 反応速度は,添加されたフォスフィン濃度に逆依存しており,フォスフィン解離がβ-水素除去に先行することを示しています.
- 主要な運動同位体効果は,速度を制限するβ-水素除去またはC-H結合形成をサポートします.
- 電子を取り除く置換剤はエノラート阻害反応に作用し,β-アルキル置換剤は速度に影響を最小限にする.
- エノラート複合体の分解速度は,類似したアルキル複合体と類似しており,違いが生じると,エノラートβ-水素の除去がより速くなります.
結論:
- ベータ水素の除去は,プラチナ (II) エノラート複合体の熱分解の重要なステップです.
- このメカニズムは,可逆的なフォスフィン解離に続いてβ-水素の除去を伴う.
- エノラ酸リガンドのステリックおよび電子要因は反応速度に影響しますが,全体的な分解率はアルキル複合体と比較できます.
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