カチオンロジウム ((I) コンプレックス・カタライズされた [3 + 2] と [2 + 1] プロパルギルエステルの電子欠乏アルキンとアルケンのサイクロアディション
Yu Shibata1, Keiichi Noguchi, Ken Tanaka
1Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Journal of the American Chemical Society
|May 22, 2010
まとめ
カチオンのロジウム ((I) 複合体は,2つの異なるサイクロアディション反応を効率的に触媒化する. プロパルギルエステルの [3+2] サイクロアディションと [2+1] サイクロプロパナーションを高収量と選択性で促進する.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- オーガニック・シンセシス オーガニック・シンセシス
背景:
- ロジウム ((I) 複合体は,有機変異における汎用的な触媒である.
- サイクル添加反応は,循環的有機分子を構成する上で極めて重要です.
- プロパルギルエステルは,価値ある合成ビルの構成要素です.
研究 の 目的:
- カチオンのロジウム ((I) 複合体, [Rh ((コッド)) ((2)) ]SbF ((6) ]の触媒活性を調査する.
- [3+2]サイクル添加反応におけるその応用を探求する.
- [2+1]サイクロプロパネーション反応におけるその有用性を検証する.
主な方法:
- 触媒として,カチオンのロジウム ((I) 複合体[Rh ((cod)) ((2)) ]SbF ((6) ]を使用しています.
- プロパルギルエステルとダイアルキルアセチレネジカルボキシラートを反応させ, [3+2]サイクル添加を行う.
- プロパルギルエステルとN,N-非置換アクリラミドを反応させ [2+1] サイクロプロパネーションを行う.
主要な成果:
- ロジウム ((I) 複合体は,プロパルギルエステルとダイアルキルアセチルネジカルボキシラートとの [3+2] サイクル添加を効果的に触媒化し,良好な収穫量で製品を生成しました.
- 同じ触媒は,プロパルギルエステルとN,N-非置換アクリラミドの [2+1] サイクル添加 (cyclopropanation) を促進した.
- サイクロプロパネーション反応は完璧なダイアステレオ選択性で進行した.
結論:
- カチオンのロジウム (((I) 複合体は, [3+2] と [2+1] のサイクル添加反応の両方に強力な触媒である.
- [3+2]サイクロアディションの触媒メカニズムは,カルボニル安定化カチオンロジウム (((I) アルケニルカルベンの中間物質を含む可能性が高い.
- この研究は,高効率性と選択性を持つ複雑な有機分子を構築するための新しい合成経路を強調しています.
関連する概念動画
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
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.
01:16Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.