オーガノセレニウム媒介の分子内ヒドロキシエテリフィケーションによる (-) - ローレフシンのバイオミテック非対称的全合成
Byungsook Kim1, Miseon Lee, Mi Jung Kim
1The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea.
Journal of the American Chemical Society
|December 4, 2008
まとめ
研究者らは,C-15アセトゲニンである (-) - ローレフシンの最初の非対称的全合成を達成しました. このバイオミテック・ヒドロキシエテリフィケーションは,合成有機化学における重要な進歩である.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 合成化学 合成化学とは
- 自然製品合成 自然製品の合成
背景:
- (-) - ローレフシンはC-15アセトゲニンで,独特の2,8-ディオキサビサイクロ[5.2.1]デカン骨格を特徴としています.
- 複雑な天然製品の合成は,ステレオ制御と効率性において重要な課題を提示します.
研究 の 目的:
- (-) - ローレフシンの最初の非対称的全合成を達成するために.
- バイオミメティック戦略を利用した新しく効率的な合成経路を開発する.
主な方法:
- 合成は,既知のオクソセンから始まる9段階の配列を用いた.
- 重要なステップは,高ステレオ選択性のための新しいオルガノセレニウム媒介バイオミメティック・ヒドロキシエテル化でした.
主要な成果:
- (-) - ローレフシンの全合成が成功しました.
- 全体で31%の収益率を達成しました.
- 合成は高いステレオ選択性を示し,天然製品の合成に不可欠です.
結論:
- (-) - ローレフシンの最初の非対称的全合成が確立されました.
- オーガノセレニウム媒介の新型ヒドロキシエセリフィケーションは,複雑なバイサイクルシステムを構築するための強力なツールです.
- この研究は,アセトゲニンの化学と合成のさらなる探索のための基盤を提供します.
関連する概念動画
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.
Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
Hydroboration-Oxidation of Alkenes
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.
Oxidation 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.
Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...


