置換されたベンジンの形成の構造と速度の研究
Jason C Riggs1, Antonio Ramirez, Matthew E Cremeens
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
Journal of the American Chemical Society
|February 26, 2008
まとめ
溶媒の選択は,ハロアリルリチウムからベンジンの形成に大きく影響する. これらの溶媒効果を理解することは,有機金属反応における地域選択性を制御するために極めて重要です.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 有機金属化学 有機金属化学
背景:
- 2-ハロアリルリチウムからベンジンの形成は,重要な合成ステップです.
- これらの除去における地域選択性は,反応条件によって影響されていることが知られている.
研究 の 目的:
- 3-置換および3,6-非置換ベンジンを形成するための除去ステップにおける溶媒依存的地域選択性を調査する.
- リチウムハライドの除去を制御するメカニズム的経路を解明する.
主な方法:
- 核磁共振 (NMR) スペクトロスコーピー (6Liと13C) で,テトラヒドロフラン (THF) のモノメア種を研究する.
- 密度関数理論 (DFT) は,解和状態と移行状態をモデル化するための計算研究である.
- 反応速度と経路を決定するための運動学的研究.
主要な成果:
- 6位に電子取り除くグループを持つ2 - ハロアリルリチウムは,THFのモノマーとして存在します.
- DFTの計算は,トリソルバート中間物質が関与していることを示唆しています.
- LiFの除去はTHF分離経路を経由し,LiClの除去は非分離経路を経由する.
- 2-クロロ-6-フッ素フェニルリチウムからLiClとLiFの除去は,競合する経路による明確な溶媒依存の地域選択性を示しています.
結論:
- ベンジン形成の地域選択性は,脱出ハリドの性質 (F対Cl) と溶媒相互作用に大きく依存しています.
- THFのモノメリックハロアリルリチウムは,溶媒とリチウムカチオンとのハリドの相互作用によって決定される経路を通じてハリドを除去します.
関連する概念動画
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In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
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For disubstituted benzene derivatives, with two groups attached to the benzene ring, three constitutional isomers are possible. For example, consider dimethyl benzene, often called xylene, where the second methyl group can be substituted at the second, third, or fourth carbon. The relative position of the substituents is represented by prefixes ortho, meta, or...