ロジウムで触媒化された,3-アシロキシ-1,4-エニンとアルキンの分子内および分子間 [5 + 2] サイクル添加で,同時に1,2-アシロキシ移行が起こります
Xing-Zhong Shu1, Xiaoxun Li, Dongxu Shu
1School of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States.
Journal of the American Chemical Society
|February 28, 2012
まとめ
新しいロジウム触媒 [5 + 2] サイクロアディション反応は,多様な7つの環を効率的に合成します. この方法では,3-アシロキシ-1,4-エニン (ACE) とアルキンが用いられ,1,2-アシロキシの独特の移動が特徴です.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
- 合成方法論 合成方法論
背景:
- 七つ組の環は,医薬品化学と材料科学における重要な支架である.
- 機能化された7つ組のリングへの効率的な合成経路は,依然として課題です.
- ロジウム触媒は,複雑な分子構造のためのユニークな経路を提供します.
研究 の 目的:
- 新しいロジウム触媒 [5 + 2] サイクル添加反応を開発する.
- 1,2-アシロキシ移行を特徴とする多様な7つ組の環を合成するために.
- 分子内および分子間反応経路の両方を探求する.
主な方法:
- 利用されたロジウム (((I)) 触媒は,カチオンおよび中性複合体を含む.
- 5炭素の成分として3アシロキシ-1,4-エニン (ACE) と2炭素の成分としてアルキンを使用しています.
- 電子が少ないリン酸塩とリン酸塩リガンドが反応効率に及ぼす影響を調査した.
主要な成果:
- ロジウムで触媒化された [5 + 2] サイクル添加反応を成功裏に開発した.
- 分子内および分子間経路を通じた7つ組の環の効率的な合成を達成しました.
- 様々なACEとアルキンとの反応の汎用性を実証した.
- リング形成に伴う1,2-アシロキシ移動が観察されました.
- 選択的機能化に適した3つの二重結合を持つ生成された製品.
結論:
- 7つ環の合成のための新しい効率的なロジウム触媒 [5 + 2] サイクロアディションを確立しました.
- 反応は独特の1,2-アシロキシ移行で進行し,複雑な構造へのアクセスを提供します.
- 開発された方法論は,様々な化学分野における潜在的な応用を持つ機能化された7つ組のリングを構築するための汎用的なプラットフォームを提供します.
関連する概念動画
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.
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.
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.
02:38Electrophilic 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.
02:47Alkynes 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.