レニウムカルボニル複合体における一酸化炭素の還元結合と,ペンダントルイス酸の結合
Alexander J M Miller1, Jay A Labinger, John E Bercaw
1Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|August 16, 2008
まとめ
フォスフィノボランリガンドは,独特のレニウムカルボニルカチオン反応性を可能にします. ハイドリド添加は新しいボロキシカルベンを形成し,これはC-Cカップリングされた製品を得るために不釣り合いです.
科学分野:
- オーガノメタリック化学
- 協調化学は,協調化学である.
背景:
- フォスフィノボランリガンドは,従来のフォスフィンリガンドと比較して,独特の電子およびステリック特性を提供します.
- レニウムカルボニル複合体は,リガンドの反応性と触媒変換を研究するための汎用的なプラットフォームです.
研究 の 目的:
- フォスフィノボランリガンドを含むレニウムカルボニルカチオンの反応性を調査する.
- ハイドリド添加によって形成された新種の有機金属種を特徴付けるために.
- 還元カルボニルリガンドにおけるC−C結合形成経路を調査する.
主な方法:
- ロニウムカルボニル複合体とフォスフィノボランリガンドの合成と特徴付け.
- ヒドリド源 (トリエチルボロヒドリドおよびプラチナヒドリド) との反応.
- 反応製品の結晶化と構造分析.
- 構造を確認するために,光譜研究 (NMR,IR) を行う.
主要な成果:
- ハイドリドをレニウムカルボニルカチオンに追加すると,レニウムボロキシカルベンが得られます.
- ボロキシカルベンは二酸化し,その結果,不釣り合いになる.
- 構造的に前例のないboroxy ((boroxymethyl) カーベンが形成され,還元されたCOリガンド間のC-C結合が特徴です.
- このC−C結合製品は,2つの同等の水素を用いて直接合成することができる.
結論:
- フォスフィノボランリガンドは,レニウムカルボニルカチオンに独特の反応性を促進し,新しいカルベンの種につながります.
- この研究は,協調された一酸化炭素リガンド間のC-C結合形成のための新しい経路を示しています.
- この発見は,有機金属カルベンの化学と還元結合プロセスの理解を広げています.
関連する概念動画
01:27Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview
Wilhelm Rudolph Fittig discovered the pinacol coupling reaction in 1859. It is a radical dimerization reaction and involves the reductive coupling of aldehydes or ketones in the presence of hydrocarbon solvent to yield vicinal diols.
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
01:09Aldehydes and Ketones to Alkanes: Wolff–Kishner Reduction
Wolff–Kishner reduction involves converting aldehydes and ketones to alkanes using hydrazine and a base. The reaction converts a carbonyl group to a methylene group. The method was independently discovered by N. Kishner in 1911 and L. Wolff in 1912. The reduction is carried out in high-boiling solvents such as ethylene glycol and diethylene glycol because heat is required to deprotonate the N–H proton in one of the reaction steps.
01:19α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview
The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an α-hydroxy ketone product. The α-hydroxy ketone is also called acyloin, so the reaction is referred to as ‘acyloin condensation.’
02:36Oxymercuration-Reduction of Alkenes
Oxymercuration–reduction of alkenes is one of the major reactions converting alkenes to alcohols. It involves the hydration of alkenes with mercuric acetate in a mixture of tetrahydrofuran and water, forming an organomercury adduct. This is followed by a demercuration step in which the adduct is reduced to an alcohol using sodium borohydride.
02:23Alcohols from Carbonyl Compounds: Reduction
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...