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Updated: Jul 11, 2026
10:03
The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids
Published on: September 30, 2014
水によって促進されるエポキシード開きカスケード
Ivan Vilotijevic1, Timothy F Jamison
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (New York, N.Y.)
|September 1, 2007
まとめ
水は,複雑な海洋天然製品を合成するために選択的エポキシド開口を促進します. この水性媒体の効果は,生物系における酵素選択性を理解する上で鍵となるものです.
科学分野:
- 有機化学 オーガニック・ケミストリー
- バイオケミストリー バイオケミストリー
- 海洋自然産物 海洋自然産物
背景:
- 伝統的な有機化学の選択性規則は,非水性環境から派生しています.
- 酵素は水性環境で機能しますが,この環境が化学的選択性に影響を与える影響は十分に理解されていません.
- 階段ポリエーテル海洋天然製品の生物合成は,提案されたエポキシド開き経路が有機溶剤で運動的に不利であるため,ステレオ化学的なパズルを提示します.
研究 の 目的:
- 階段ポリエーテル海洋天然製品のステレオ選択合成における水質媒体の役割を調査する.
- 提案された生物合成経路の運動的実現可能性に関する20年前のパズルを解決するために.
- これらの天然製品のコア構造への高収量合成経路を確立する.
主な方法:
- 選択性を促進するために,中性水を反応媒介として利用する.
- テトラヒドロピラン (THP) グループをテンプレッティングして,エポキシードリング開き反応を導く.
- 水中のエポキシードカスケード反応の動的好意性を調査する.
主要な成果:
- 中性水は,エポキシード鎖の望ましいリング開き選択性のための最適なプロモーターとして作用します.
- 一つのテンプレート THP グループは,選択的なカスケードを開始するのに十分です.
- 階段ポリエーテルコアのための高収量合成戦略が開発されました.
結論:
- 水媒体の効果は,有機合成において特定の選択性を達成し,酵素処理を反映するために極めて重要です.
- この発見は,複雑な海洋天然製品への有効な合成経路を提供します.
- この研究は,生物触媒と有機合成における反応媒介としての水の重要性を強調しています.
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02:23Autoxidation of Ethers to Peroxides and Hydroperoxides
Ethers represent a class of chemical compounds that become more dangerous with prolonged storage because they tend to form explosive peroxides when standing in the air. Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly oxidize to form hydroperoxides and dialkyl peroxides.
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.
01:46Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
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...
02:24Acid-Catalyzed Ring-Opening of Epoxides
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...
02:26Base-Catalyzed Ring-Opening of Epoxides
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...