1,5-酸素ブリッジ付きの中型カーボサイクルの原子効率の良い組立は,Ru-触媒化されたアルキン-アルケンのカップリングとプリンス型サイクリングの連続的な組み合わせによるものです
Fernando López1, Luis Castedo, José L Mascareñas
1Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain.
Journal of the American Chemical Society
|April 19, 2002
まとめ
ルテニウム触媒は,単純な前駆体から酸素橋渡しカルボサイクルの効率的な合成を可能にします. この新しい方法により,以前は入手が困難だった複雑な8つまたは9つ環の構造にアクセスできます.
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:
- 中型カーボサイクルの製造 (8,9本のリング) は,依然として合成的な課題です.
- 1,5-酸素ブリッジされたカルボサイクルの合成のための既存の戦略は,範囲と効率において限られています.
研究 の 目的:
- 新しく効率的な合成ルートを開発し,1,5-酸素のブリッジ付きの8つ,9つ構成のカーボサイクルを開発する.
- 容易に入手可能な出発材料と確立された触媒方法を使用する.
主な方法:
- 1-トリメチルシリル-1-アルキン-3-オールとアルリルエチルエーテルをルテニウム触媒で結合する.
- クープリングされた製品のイン・シットーケチゼーション.
- ルイス酸誘発サイクライゼーションにより,カルボサイクリックフレームワークが形成されます.
主要な成果:
- 1,5-酸素の橋渡しによる8つ,9本のカーボサイクルの合成に成功しました.
- この方法は,アクセシブルな出発材料と触媒ルテニウムシステムを使用しています.
- サイクリングは,ルイス酸触媒の下で効率的に進行します.
結論:
- 複雑なカーボサイクルの構築のための新しい合成戦略が確立されました.
- この方法は,困難な1,5-酸素ブリッジリングシステムにアクセスするための貴重な代替手段を提供します.
- 記述されたアプローチは,合成有機化学者のツールキットを拡張します.
関連する概念動画
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
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.
01:16Cycloaddition 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.
03:00Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
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.
02:36Oxymercuration-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.