平面化されたトリアリルボラン:構造的制約による安定化と平面からボウルへの変換
Zhiguo Zhou1, Atsushi Wakamiya, Tomokatsu Kushida
1Department of Chemistry, Graduate School of Science, Nagoya University and JST-CREST, Furo, Chikusa, Nagoya 464-8602, Japan.
Journal of the American Chemical Society
|February 29, 2012
まとめ
フライデル・クラフトス循環で合成された新しいトリフェニルボラン化合物は,驚くべき安定性とユニークな電子特性を示しています. これらの分子は,フッ化物イオン処理で制御された形状変化を経験し,材料科学における潜在的な応用を提供します.
科学分野:
- オルガノボロン化学 オルガノボロン化学
- オーガニック・シンセシス オーガニック・シンセシス
- マテリアルサイエンス 材料科学
背景:
- トリフェニルボランの誘導体は,独自の電子および光物理的特性で知られています.
- オーガノボロン化合物の分子幾何学を制御することは,それらの特性を調節するために非常に重要です.
研究 の 目的:
- 新型トリフェニルボランおよびディボラアントラセンの誘導体を限られた平面配列で合成する.
- これらの新しい化合物の安定性と性質を調査する.
- 外部刺激,特にフッ素イオンに対する反応を調査する.
主な方法:
- 合成のための内分子複合フライデル・クラフトス循環化.
- 構造的,電子的,そして光物理的性質の特徴.
- 形状の変化を誘発するフッ化物イオン処理.
主要な成果:
- 平面型トリフェニルボランとディボラアントラセンの化合物の合成が成功しました.
- 空気,水,アミンに対する安定性が実証されています.
- 観察された特徴的な電子的および光物理的行動.
- フッ化物イオン添加で制御された平面からボウルへの変換を達成しました.
結論:
- 合成された化合物は固有の安定性と調節可能な性質を持っています.
- 簡単な平面からボウルへの変換は,分子スイッチングのための新しいメカニズムを提供します.
- これらの発見は,先進的なオルガノボロン材料の開発に寄与する.
さらに関連する動画
関連する概念動画
02:11Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:02Chair Conformation of Cyclohexane
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
02:36Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.