極性増強により可能となる遠隔メチレン部位での高度選択性C ((sp3) -H結合酸化
Sergio Sisti1, Marco Galeotti2, Filippo Scarchilli2
1Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata", Via della Ricerca Scientifica, 1, I-00133 Rome, Italy.
Journal of the American Chemical Society
|September 26, 2023
まとめ
この研究は,マンガンの触媒と過酸化水素を用いた選択的なC ((sp3) -H結合の酸素化のための新しい方法を示しています. この反応は,様々な基板,特に水素結合ドナー溶媒の遠隔位置で高収量と場所選択性を達成する.
科学分野:
- 有機化学
- カタリシス
- 合成方法論
背景:
- C ((sp3) -H結合の選択的機能化は,有機合成における重要な課題である.
- 酸化反応は酸素を含む機能群の導入に不可欠である.
- 複数の類似のC−H結合を含む反応における部位選択性を制御することは困難である.
研究 の 目的:
- H2O2と[Mn{OTf}2{TIPSmcp}]触媒を用いて,サイクロアルキルおよび1アルキル基板のC{sp}-H結合酸化を調査する.
- 水素結合ドナー (HBD) 溶媒が反応率と場所選択性に与える影響を評価する.
- 遠隔メチレン部位に対する予測可能で高度に部位選択的な酸化方法を開発する.
主な方法:
- 水素過酸化物 (H2O2) を用いて電子取り除く機能群 (EW FG) を有する基板の触媒酸化
- アセトニトリル (MeCN) と1,1,3,3-ヘクサフッロ-2-プロパノール (HFIP) とノンフッロートルビュチルアルコール (NFTBA) のような強いHBD溶剤で実施された酸化反応の比較
- 異なるメチレン位置での酸化のための製品比 (PR) とサイト選択性の分析.
主要な成果:
- 様々な基板の遠隔メチレン基部では,高収量と前例のない部位選択性 (> 99%) が達成された.
- MeCNからHBD溶媒 (HFIP,NFTBA) に移行すると,サイト選択性が著しく増加した.
- EWGと溶媒の水素結合によって引き起こされる"極性強化"効果は,観察された選択性を合理化します.
結論:
- 遠隔C ((sp3) -H結合のサイト選択的酸化のためのシンプルで軽い,非常に効果的な手順が開発されました.
- この方法は,幅広い基板範囲を示し,選択性に対する予測可能な制御を提供します.
- このアプローチは,合成有機化学の強力な新しいツールを提供します.
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