テトラヒドロボラートからアルキニル-アミノボリル中間体を通じたアミノボリルビニリデン-オスミウム複合体へ
María L Buil1, Miguel A Esteruelas, Karin Garcés
1Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain. mbuil@unizar.es
Journal of the American Chemical Society
|January 29, 2011
まとめ
アミノボリルリガンドを持つオスミウム複合体は,アルキンや酸で変換される. これらの反応により,新しいボリル誘導体とビニリデネ複合体が生み出され,有機金属化学における新しい反応性を示した.
科学分野:
- 有機金属化学 有機金属化学
- 無機化学 無機化学とは
- カタリシス カタリシス カタリシス
背景:
- オスミウム複合体は合成変換において多用途である.
- テトラヒドロボラートリガンドは,ユニークな反応経路を提供しています.
- アミノボリルとアルキニルリガンドは,有機金属合成における重要な機能群である.
研究 の 目的:
- オスミウムテトラヒドロボラート複合体の,アミンおよびアルキンとの反応性を調査する.
- 新種のアミノボリルおよびアミノ (((フッ素)) ボリルオスミウム誘導体の形成を調査する.
- これらの複合体の後の変容を様々な条件下で研究する.
主な方法:
- オスミウムテトラヒドロボラート複合体の反応 (1) 主要アミン (アニリン,p-トルウイジン) と.
- 結果となるアミノボリル複合体をフェニラセチレンで処理する.
- さらに,テトラフルオロボリック酸 (HBF(4) 酸エステン酸,一酸化炭素 (CO) による反応が行われます.
- 製品のスペクトロスコーピカル特徴付け (NMR,X線微分)
主要な成果:
- 複合体1とアミンからアミノボリルオスミウム複合体 (2, 3) の合成.
- フェニラセチレンとの反応によるアルキニル-アミノボリルオスミウム複合体の形成 (4,5).
- HBFを使用したアミノ・フッ素・ボリル種 (6, 7) に変換する (4).
- 酸エステンまたはCOを加えると6座標複合体 (8-11) の生成.
- アミノボリルビニリデン (12,13) と関連するフッ素誘導体 (17,18) につながる1,3-ボリル移行の観察.
結論:
- オスミウムテトラヒドロボラート複合体は,アミンおよびアルキンに対して豊富な反応性を示す.
- オスミウム複合体の多種多様な機能化は達成可能であり,アミノボリル,アミノ (((フッ素)) ボリル,およびヴィニリデン誘導体につながる.
- この研究は,オスミウムの化学における新しい移動的挿入と再配置の経路を強調しています.
関連する概念動画
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.
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.
02:36Regioselectivity 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.
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
01:26Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
01:16Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...