アルキネスのアニオンとラジカル環閉塞の規則
Igor V Alabugin1, Kerry Gilmore, Mariappan Manoharan
1Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, 32306-4390, United States. alabugin@chem.fsu.edu
Journal of the American Chemical Society
|June 17, 2011
まとめ
この研究は,ボルドウィン・ボールドウィンを改訂しています.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 反応メカニズム 反応メカニズム
- ステレオ化学 ステレオ化学
背景:
- ボールドウィンのルールは,リングのサイズと攻撃軌道に基づいて好ましいサイクリングモードを予測します.
- アルキンの核好性および急性サイクルを制御するステレオ電子的要因が再検討されています.
研究 の 目的:
- アルキーンサイクライゼーションにおける好ましい攻撃軌道のステレオ電子的基礎を再評価する.
- 固有のステレオ電子的好みを,製品形成における熱力学的安定性と比較するために.
主な方法:
- マーカス理論を用いて,活性化バリアを内在的および熱力学的成分に分解する.
- さまざまな核愛体のサイクライゼーション選択性の計算分析.
- 既知のサイクライゼーション反応の実験的観測と比較.
主要な成果:
- 固有の結合形成のために,急性軌道 (エンドディグ) よりもステレオエレクトロニック的に好ましいのは,オブツー攻撃軌道 (exo-dig) です.
- エンドプロダクトの熱力学的安定性は,より小さなリングに対する本質的な好みを隠すことができます.
- 予測は,3 exo-dig と 4 exo-dig のサイクライゼーションの実験データと一致し,ボールドウィンの規則に反する.
- 炭素,窒素,酸素を中心とした核好性に対する計算された選択性は,外位数偏好を示している.
結論:
- 固有のステレオエレクトロニックの好みは,従来のボールドウィンのルールに異議を唱えて,エクソディグの閉鎖を好む.
- 熱力学的要因は,特に小さな環の形成において重要な役割を果たします.
- この発見は,核愛性経路と激素経路の両方に適用可能な,アルキーンサイクルに対するより正確な立体電子モデルを提供します.
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