(ヘテロ) アリルボロンエステルのプロトデボロネーション:直接対前水解経路と自己/自己触媒
Hannah L D Hayes1, Ran Wei1, Michele Assante2
1EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
Journal of the American Chemical Society
|August 30, 2021
まとめ
ボロンエステルは基本条件では微妙な安定性を示し,エステル化が常にボロン酸と比較して安定性を高めるという仮定に異議を唱える. 水解は,pKaの近くの触媒によって影響される,プロトデボレーションの重要な部分である.
科学分野:
- 有機化学
- 物理化学
- 反応運動学
背景:
- ボロン酸とそのエステルは,有機合成と医薬品化学において極めて重要です.
- 様々な条件下でボロンエステルの安定性と反応性を理解することは,その有効な適用に不可欠である.
- ボロン酸と比較してボロンエステルの安定性の向上に関する一般的な仮定は,批判的な評価を必要としています.
研究 の 目的:
- 塩基触媒による水解と様々なボロンエステルのプロトデボロネーションの運動学とメカニズムを調査する.
- 水性有機介質におけるボロンエステルの安定性を影響する要因を解明する.
- ボロンエステルとそれに対応するボロン酸の安定性を比較する.
主な方法:
- 現場および停止フローのNMRスペクトル (19F,1H,11B)
- pH率に依存する研究
- イソトープ誘導実験とデウテリウム運動イソトープ効果 (2H KIEs)
- コーン・シャム密度関数理論 (KS-DFT) による計算.
主要な成果:
- 基本的水性有機条件下でのボロンエステルの安定性は非常に微妙である.
- エステル化は,親ボロン酸よりも高い安定性を普遍的に与えません.
- エステルからボロン酸への水解は,プロトデボロン化における重要な経路である.
- 自己,自己,そして酸化触媒は,pKaの近くのプロトデボロネーションを加速することができます.
結論:
- ボロンエステルの安定性は文脈に依存し,常にボロン酸に優れているわけではありません.
- 水解は,ボロンエステルのプロトデボロン化における重要な中間段階である.
- 触媒効果は,特定のpH条件下でのボロンエステルの反応性において重要な役割を果たします.
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