ビスムス媒介の2組分ヘミアセタル/オクサ結合添加反応によるシン-1,3-ダイオキサンのダイアステロ選択的構成
P Andrew Evans1, Aleksandr Grisin, Michael J Lawler
1Department of Chemistry, The University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom. Andrew.Evans@liverpool.ac.uk
Journal of the American Chemical Society
|February 3, 2012
まとめ
この研究は,シン-1,3-ダイオキサンを生成するためのシンプルで効率的なビスムート触媒反応を紹介しています. この方法は,直接的に貴重な電子を取り除くグループを形成し,合成経路を簡素化します.
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:
- 複雑な有機分子の立体選択合成は,薬剤発見と材料科学において極めて重要です.
- 1,3-ダイオキサンのようなヘテロサイクルの化合物を構築するための効率的な触媒的方法の開発は,依然として活発な研究分野です.
- ビスムート触媒は,従来の重金属触媒よりも,よりグリーンで,しばしばより選択的な代替手段を提供します.
研究 の 目的:
- 新しく高度に効率的でステレオセレクティブなシン-1,3-ダイオキサン合成方法を開発する.
- 2つの成分ヘミアセタル/オクサ結合添加反応におけるビスムート触媒の有用性を調査する.
- 酸化状態の調整を必要とせず,電子を取り除くグループの直接導入を実証する.
主な方法:
- ビスムート触媒を用いて,δ-トリアルキルシリロキシ/δ-ヒドロキシα,β-不飽和アルデヒド/ケトンとアルキルアルデヒドの反応を媒介する.
- ヘミアセタル形成を伴う2つの成分反応戦略を採用し,その後オキサ結合添加を行う.
- 標準的なスペクトロスコーピテクニックを用いて,生成されたシン-1,3-ダイオキサン製品を特徴づける.
主要な成果:
- syn-1,3-dioxanes.の非常に効率的でステレオ選択的合成を達成しました.
- 開発されたプロトコルの操作のシンプルさを実証しました.
- 電子を取り除くグループを持つ分子に直接アクセスし,多段階の酸化プロセスを回避しました.
結論:
- ビスムート媒介反応は,有価なシン-1,3-ダイオキサン誘導体への強力で直接的な経路を提供します.
- この方法論は,効率性,ステレオ選択性,合成収束という点で重要な利点を提供します.
- 機能群を直接インストールするプロトコルの能力は,複雑な分子合成を簡素化します.
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
関連する概念動画
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.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
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01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
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...
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
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.