パラジウム触媒によるオキシラン開き反応は,C-H結合活性化によるアレンと発生する
Zhen Wang1,2, Yoichiro Kuninobu1,2, Motomu Kanai1,2
1†Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|April 30, 2015
まとめ
研究者らは,C-H活性化とC-C結合のための新しいパラジウム触媒反応を開発した. この効率的な方法は,室温で動作し,様々な機能群を許容し,価値のある製品を生成します.
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:
- 直接的なC-H機能化は,化学合成に対するより原子経済的なアプローチを提供します.
- オキシランは多用途の構成要素ですが,C−H結合と直接結合することは依然として困難です.
- 移行金属の触媒は,新しい結合形成反応の開発に不可欠です.
研究 の 目的:
- 芳香C-H結合とオキシラネの間のパラジアム触媒による新種の分子間直接結合反応を開発する.
- 機能化された有機分子を合成するための多用途かつ効率的な方法の確立.
- C-H活性化/C-C結合プロセスのメカニズムを調査する.
主な方法:
- パラジウムで触媒化されたCH活性化反応.
- アレーン (指向グループを含む) とオキシラネンの結合.
- 反応条件の最適化 (温度,添加物).
- 運動イソトープ効果実験を含むメカニズム研究.
主要な成果:
- パラジウム触媒によるC-H活性化/アレンとオキシランのC-C結合が達成された.
- 反応は,添加物なしで室温で進行し,良質から優れた収量が得られます.
- 幅広い機能群への耐性が実証され,グラムスケールへのスケーラビリティがあります.
- C-H活性化による芳香C-H結合とオキシラン間の分子間直接結合の最初の例です.
- N-メトキシベンザミドを使用した1つのポットで合成された3-置換されたイソクロマン-1-オン.
- 結合反応中に観測されたステレオレテンション.
- 運動同位体効果の実験では,速度を決定するステップとしてC-H結合の活性化を示している.
結論:
- C-H活性化によるアレンとオキシランの新しく効率的なパラジウム触媒による直接結合を開発した.
- この方法は,穏やかな条件下で複雑な有機分子への多用途な経路を提供します.
- 機械学的研究は,C-H結合の割れが速度を制限するステップであり,将来の触媒設計のための洞察を提供することを示唆しています.
さらに関連する動画
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
09:12[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
10.0K
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
11:44Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
26.0K
関連する概念動画
02:26Base-Catalyzed Ring-Opening of Epoxides
11.1K
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
11.1K
02:24Acid-Catalyzed Ring-Opening of Epoxides
9.9K
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
9.9K
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
8.2K
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.
8.2K
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
13.7K
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.
13.7K
03:08Hydroboration-Oxidation of Alkenes
12.6K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
12.6K
03:00Preparation of Epoxides
9.9K
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...
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...
9.9K