C結合ボロンエノラートの合成と応用
Elvis Wang Hei Ng1, Kam-Hung Low1, Pauline Chiu1
1Department of Chemistry, and the State Key Laboratory of Synthetic Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , People's Republic of China.
Journal of the American Chemical Society
|February 27, 2018
まとめ
研究者は安定したC結合ボロンエノラートを合成するための新しい方法を開発しました. これらの化合物は初めて分離され,新しい炭素-酸素と炭素-炭素結合を形成するユニークな反応性を示しています.
科学分野:
- 有機化学
- オーガノボロン化学
背景:
- ボロンエノラートは典型的にはO結合であり,C結合イソメアはよりまれで,しばしば不安定である.
- C結合ボロンエノラート合成の既存の方法は,範囲と効率が限られている.
研究 の 目的:
- 非四分化C結合ボロンエノラートを製造するための一般的かつ簡単な方法を開発する.
- これらの新しいC結合ボロンエノラートを特徴づけ,その反応性を探求する.
主な方法:
- ボールエノラートのリガンド制御O-to-Cイソメリゼーション
- C結合ピナコルボロンエノラートの分離と浄化
- NMR光学とX線結晶学を用いた特徴付け.
主要な成果:
- 新しいイソメリゼーションプロトコルによる未四分化C結合ボロンエノラートの製造に成功した.
- 純粋なC結合ピナコルボロンエノラートを初めて分離した.
- C結合ボロンエノラートの安定性を証明する.
- O結合ボロンエノラートと比較して明確な反応性のパターンの観察.
結論:
- 安定したC結合ボロンエノラートを合成するための一般的で簡単な方法が確立されています.
- C結合ボロンエノラートは安定しており,独特の反応性プロファイルを持っています.
- これらのC結合ボロンエノラートは,C−OとC−C結合形成のための有価な合成中間物質である.
関連する概念動画
Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
4.6K
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an...
4.6K
Alkylation of β-Diester Enolates: Malonic Ester Synthesis
4.2K
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
4.2K
Types of Enols and Enolates
3.7K
Aldehydes and ketones form enols, although only about 1% of the enol is present at the equilibrium for simple monocarbonyl compounds. The enol form is undetectable for acetaldehyde, present as only 1.5 × 10−4 % of acetone, and present as only 1.2% of cyclohexanone. Two kinds of regioisomeric enols are possible for unsymmetrical ketones, and their net composition is 1% at equilibrium. This instability is due to the lower bond energy of C=C than the C=O group. The additional...
3.7K
Reactivity of Enols
4.2K
Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A carbonyl compound with an α hydrogen undergoes keto–enol tautomerism and remains in equilibrium with its tautomer, the enol form. Usually, the keto tautomer is present in a higher concentration than the enol tautomer due to the higher bond energy of C=O compared to C=C. Moreover, the direction of the keto–enol equilibrium is...
4.2K
Enolate Mechanism Conventions
3.0K
When a carbonyl compound is treated with a strong base, the α position gets deprotonated to give a resonance-stabilized intermediate called an enolate. Enolates are ambident nucleophiles because they possess two nucleophilic sites that can attack an electrophile owing to the delocalization of the negative charge between the α carbon and oxygen atoms. When the oxygen atom attacks an electrophile, it is called O-attack, whereas electrophilic attack via the α carbon is known as...
3.0K
Reactivity of Enolate Ions
3.4K
Enolate ions are formed by the acid–base reaction of a carbonyl compound with a base. This leads to deprotonation of the α hydrogen atom, leading to a resonance-stabilized enolate ion where one of the contributing structures is an oxyanion, which imparts additional stability. Therefore, the proton on the α carbon is more acidic in nature than that of other sp3-hybridized C–H bonds but less acidic than those in O–H bonds where the negative charge in the conjugate...
3.4K


