チェレーションによる制御によるオーガノシンをα-クロロアルジミンに添加する
Gretchen R Stanton1, Per-Ola Norrby, Patrick J Carroll
1Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
Journal of the American Chemical Society
|September 26, 2012
まとめ
この研究は,炭素-ハロゲン結合が化学反応におけるステレオ化学を制御する方法を明らかにしています. アルキル亜鉛ハリドは基板に連携し,ケラート制御による高度にダイアステロ選択性の炭素-炭素結合形成を可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- ステレオ化学 ステレオ化学
- 有機金属化学 有機金属化学
背景:
- α-ハロカルボニル化合物に核性添加を加えると,通常,非ケラ化経路を通ってCornforth-Evans製品が得られます.
- C-C結合形成におけるダイアステロセレクティブ性は,複雑な分子の合成に不可欠である.
研究 の 目的:
- 金属媒介C-C結合形成中のダイアステレオ選択性を逆転させるC-X結合の前例のない役割を調査する.
- α-クロロアルジミンへのオーガノジン添加物におけるC-X結合を含むケレーション制御を実証する.
主な方法:
- α-クロロアルディミン基板にオルガノジン反応剤を添加する.
- アルキル亜鉛ハリドルイス酸を金属の協調に利用する.
- 機械論的仮説を裏付けるための計算学的研究を用いること.
主要な成果:
- α-クロロアルジミンにオーガノジン反応剤の高度なダイアステロセレクティブ添加が実証されています.
- 典型的なステレオ化学的結果を逆転させ,C-X結合によって介在するケレーション制御を示した.
- 識別されたアルキル亜鉛ハリドルイス酸は,基質のCl,N,O原子に連携しています.
結論:
- C-X結合は,金属の協調 (ケラチオン制御) を通して,立体化学の制御に積極的に参加することができる.
- このメカニズムは,C−C結合形成反応において高いダイアステロ選択性を達成するための新しい戦略を提供します.
- この発見は,有機合成におけるステレオ化学的制御の理解を広げている.
関連する概念動画
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
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02:46Halogenation of Alkenes
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01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
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01:27Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
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Direct addition products are formed faster owing to...
01:14α-Halogenation of Carboxylic Acid Derivatives: Overview
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