炭酸塩中のボロン中心の急性物質の酸化生成
Harrison A Mills1, Joshua L Martin1, Arnold L Rheingold2
1Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
Journal of the American Chemical Society
|February 20, 2020
まとめ
研究者らは,前駆体酸化により,ボロン頂点を中心としたカルボラニル基を生成した. これらの新種のラジカルは,カルボランの新しい置換反応を可能にし,さまざまなボロンを含む化合物を生み出します.
科学分野:
- 有機金属化学
- ボロン化学
- ラジカル・ケミストリー
背景:
- カーボランは独特の電子特性を持つケージ状のボロンクラスターです.
- カーボランの機能化は,新しい材料と触媒の開発に不可欠です.
- カーボランの直接的な根基ベースの機能化方法は限られている.
研究 の 目的:
- ボロンの頂点中心のカルボラニル基の間接的な観察と利用を報告する.
- カーボランを基質介質で機能化するための新しい方法を確立する.
- 様々な基質に対するこれらのラジカルの反応性を探求する.
主な方法:
- 改変したカルボラニル前駆体による酸化によるカルボラニル基の生成
- 酸化は,ボロンクラスターケージとエクソポリエドール置換体間のB-B結合を標的とする.
- 発生した根性種のインサイト特徴と反応.
主要な成果:
- ボロンの頂点中心のカルボラニルラジカルの間接的な観察と使用の成功.
- 酸素基のラジカル,二カルコゲニド,N-ヘテロサイクルの反応性が実証されている.
- 新しいB-O,B-S,B-Se,B-Te,B-C結合を備えた合成された置換カルボラン.
- 電子が豊富で,電子が少ないB-H頂点の両方で容易な置換化学を達成しました.
結論:
- カーボラニル前駆物質の酸化により,反応性ラジカル中間産物へのアクセスが可能となる.
- これらのカルボラニルラジカルは,カルボランの機能化のための多用途のプラットフォームを提供します.
- 開発された方法は,カーボラン頂点の多様な電子環境に適用できます.
関連する概念動画
03:08Hydroboration-Oxidation of Alkenes
10.8K
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.
10.8K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.3K
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.
9.3K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
20.5K
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.
20.5K
00:47Radical Formation: Addition
2.1K
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
2.1K
01:07Radicals: Electronic Structure and Geometry
4.9K
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
4.9K
01:17Radical Anti-Markovnikov Addition to Alkenes: Mechanism
4.5K
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
4.5K