離子液中のポリボラン反応:機能化されたデカボランとオカルボランのクラスターへの新しい効率的な経路
Upal Kusari1, Yuqi Li, Mark G Bradley
1Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Journal of the American Chemical Society
|July 15, 2004
まとめ
デカボラン反応は,水酸化とアルキン挿入のような反応が,現在,触媒なしでイオン性液体で効率的に発生しています. これにより,機能化されたデカボランとオカルボランのクラスターに新しい,高生産性の合成経路を提供します.
科学分野:
- 有機金属化学 有機金属化学
- グリーン・ケミストリー 緑の化学
背景:
- 伝統的な有機溶媒は,デカボラン反応のために,しばしば触媒を必要とします.
- イオン性液は,反応機構に影響を与えるユニークな溶媒特性を有しています.
研究 の 目的:
- デカボランオレフィン-ヒドロボレーションとアルキン-挿入反応をイオン性液体溶媒で調査する.
- これらの反応がイオン性液体内の触媒なしで進行できるかどうかを判断する.
- 機能化されたボロンクラスターのための新しい合成経路を確立する.
主な方法:
- デカボランをオレフィンでイオン性液体溶媒で水酸化する.
- アルキン挿入反応をデカボランでイオン性液体媒体で実施する.
- 反応製品を分析して,機能化されたクラスターの形成を確認する.
主要な成果:
- デカボラン・オレフィン・ヒドロボレーションとアルキン挿入反応は,イオン性液体内の触媒なしで進行した.
- 機能化されたデカボランとオカルボランのクラスターの高収量が得られた.
- 反応は,従来の有機溶媒の反応と比べて,著しく異なる行動を示した.
結論:
- イオン性液体溶媒は,触媒のないデカボラン反応を促進する.
- これらの発見は,ボロンクラスター化学のための新しい,効率的な合成の道を開きます.
- この研究は,オルガノボロン化合物の合成方法論の進歩におけるイオン性液体の可能性を強調しています.
関連する概念動画
Hydroboration-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.
Regioselectivity 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.
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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.
Preparation of Alcohols via Addition Reactions
Overview
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
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