We gratefully acknowledge the Swedish Research Council Formas for generous financial support.

メチル6-オキソ3,4,6- triphenylhexanoateの1グラムスケールの合成<ol><li> 10ミリバール、1時間、40℃でロータリーエバポレーター上で丸底フラスコ中で乾燥した1-エチル-3-メチルイミダゾリウムアセテート（EMIMAc）。 </li><li> 100 mlの乾燥EMIMAc 2.1gのと1.0gの1,3-ジフェニル-2-プロペン-1-オンを追加し、マグネチックスターラーを備えた丸底フラスコ。 </li><li>フラスコにメタノールの2.019ミリリットルとシンナムアルデヒドの2.3グラムを追加します。 </li><li>室温（22℃）で1分間撹拌し、ジクロロメタン60ml中の混合物を溶解します。 </li><li>続いて攪拌混合物（ステップ1.4）に1.8 mlの0.37ジアザビシクロ[5.4.0]ウンデカ-7-エン（DBU）を追加し、丸底フラスコをキャップ。 </li><li>室温（22℃）で500回転の速度で磁気攪拌棒で攪拌します。 </li><li> 1 H-NMR。7.8 ppmの領域でカルコンの二重結合の消失のための24ルックとの反応の完了を確認してください。 </li><li>反応に達したとき<html>完成は10ミリバール、15分間20℃で回転蒸発器上で揮発性物質を除去。 </li><li>磁気撹拌棒で撹拌することによりEMIMAcを溶解残渣にメタノール50mlを追加します。 </li><li> 30分間750回転の速度で磁気攪拌棒を激しく撹拌することにより、フラスコの壁から固形物を除去します。必要に応じて、壁から残りの固形物を除去するために、スパチュラを使用しています。 </li><li>フリット（孔径3）の混合物をフィルタリングします。 </li><li>追加のメタノール20mlで洗浄します。 EMIMAcのリサイクルを希望する場合は、メタノールろ液を蒸発させます。 （ステップ2.1）。 </li><li>それでもフリットで、穏やかにスパチュラで小片に（ステップ1.11）からフィルターケーキを分割し、予め秤量した丸底フラスコに粉末漏斗を介して固体を移し、真空下で固体を乾燥させます。 </li><li>フラスコの重量を測定し、歩留まりを計算します。 </li><li> 1 H NMR（ステップ1.7）で製品を分析します。報告のスペクトルと比較してください。24 </li></ol>EMIMAcのタイトル &quot;&gt; 2。リサイクル<ol><li> 30分間40℃で、10ミリバールの減圧下で（ステップ1.12から）のメタノール混合物から揮発性物質を除去します。 </li><li> EMIMAcが存在することを確認するには、1 H NMRおよび13 C NMRによって得られた油を分析します。24 </li><li>ステップ1.2から始まるリサイクルEMIMAcを使用してください。 </li></ol> 3.ゲル化<ol><li>ストック溶液の調製<ol><li>バイアルにメチル6-オキソ3,4,6- triphenylhexanoate（ステップ1.15）からの生成物および磁気撹拌棒を200mg追加します。ケトエステルを溶解させるために2.0ミリリットルのジクロロメタンを追加します。すべてが溶解するまで撹拌します。 </li></ol></li><li>ゲル化<ol><li> 500ミリリットルのビーカーに50mlのヘプタンを追加します。ヘプタンにストック溶液1.5mlを加えます。十分な混合を確保し、ゲル化が起こるまで周囲温度で撹拌することなく放置する迅速に攪拌します。 </li></ol></li></ol>

<ol>
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The authors have nothing to disclose.

ケトエステル3のX線分析およびボード線図および共同研究者30により提案されたメカニズムの調査に決定抗 -配置に基づいて、次の反応経路は、（ 図5）を提案しています。 ILの脱プロトン化は、NHC種を生成します。 NHCは、ブレスロー中間I.ザブレスロー中間体を形成する不飽和アルデヒドと反応し、カルコンはジエンIIを形成するために、クロスベンゾイン反応で?...

<img alt="目次1" src="/files/ftp_upload/53213/53213TOC.jpg" /> （上）1,6-ケトエステルの三成分合成：低分子量ゲル化剤の新しいクラス。 イオン液体（ILS）は、高安定性、低揮発性、非可燃性を有し、従って、リサイクルのための安全な反応媒体との理想的な溶剤として注目を描画している。1-3ジアルキルイミダゾリウムイオン性液体の特定のタイプであること、塩基の存在下で、N-複素環カルベン（NHC）をレンダリングするために脱プロトン化することができる。有機触媒の分野では4、NHCSは、明確な反応経路の下で動作し、一般的な反応の広い範囲に広範囲に使用を発見した。5月11日 これにもかかわらず、イオン液体およびCC結合forminとの間の接続G-NHC触媒反応は比較的未開拓です。それにもかかわらず、イオン液体由来NHCSは、ベンゾイン縮合とSTETTER反応などの反応を形成するC-C結合を触媒することが報告されている。12-22、例えば、DavisらN-アルキルthiazoliums由来のILがでプレ触媒として機能することを示しましたベンズアルデヒドからベンゾインを形成する。12 より最近では、Chenおよび共同研究者は、ILベースイミダゾリウムを使用してこの概念を拡張し、1-エチル-3-メチルイミダゾリウムアセテート（EMIMAc）、5,5 &#39;を生成するために、5-ヒドロキシメチルフルフラール（HMF）にベンゾイン縮合を行うためにジ（ヒドロキシメチル）furoin（DHMF）。23のILは、市販されており、NHCSを生成する安価な方法を提供することを考えると、我々は反応のILの他の種類が行うことができるものを調査に興味を持っていました。この目的のために、我々は、ジアルキルイミダゾリウムを効率的に正式な共役additiでプレ触媒として使用することができることを見出しました1,6-ケトエステルを与えるカルコンに不飽和アルデヒド（ 図1）の上。最も効率的なIL、EMIMAcは、シンナムアルデヒドとカルコンの間で高度に立体選択的反応を促進します。反応は 、抗-ジアステレオマーのために高い優先的に発生し、1,6-ケトエステルは、92％までの収率で単離することができる。24,25,26 <img alt="図1" src="/files/ftp_upload/53213/53213fig1.jpg" /> 図1：三成分、カルコンにシンナムアルデヒドの立体選択的付加を、IL-媒介。

<table><tbody><tr><td>1-ethyl-3-methyl imidazolium acetate</td><td>Aldrich</td><td>51053-100G-F</td><td>Produced by BASF &amp;ge;90%, dried on a rotary evaporated before use (10 mBar, 40 &amp;deg;C, 1 hr)&lt;br/&gt; CAS NUMBER: 143314-17-4</td></tr><tr><td>1,3-diphenyl-2-propen-1-one</td><td>Aldrich</td><td>11970-100G</td><td>98.0%&lt;br/&gt; CAS NUMBER: 94-41-7</td></tr><tr><td>trans-cinnamaldehyde&amp;nbsp;</td><td>Aldrich</td><td>C80687-25G</td><td>99%, stored under nitrogen prior to use&lt;br/&gt; CAS NUMBER: 14371-10-9</td></tr><tr><td>1,8-Diazobicyclo[5.4.0]undec-7-ene</td><td>Aldrich</td><td>139009-25G</td><td>98%&lt;br/&gt; CAS NUMBER: 6674-22-2</td></tr><tr><td>Methanol</td><td>Sigma-Aldrich</td><td>32213N-2.5L</td><td>puriss. P.a., ACS reagent, reag. ISO, reag. Ph. Eur. &amp;ge;99.8% (GC)&lt;br/&gt; CAS NUMBER: 67-56-1</td></tr><tr><td>Dichloromethane</td><td>Fischer Chemical</td><td>D/1852/17X</td><td>Analytic reagent grade, stabilized with amylene&lt;br/&gt; CAS NUMBER: 9/2/1975</td></tr><tr><td>n-Heptane</td><td>Fischer Chemical</td><td>H/0160/17X</td><td>Analytic reagent grade&lt;br/&gt; CAS NUMBER: 142-82-5</td></tr></tbody></table>

highly stereoselective synthesis of 1,6-ketoesters mediated by ionic liquids: a three-component reaction enabling rapid access to a new class of low molecular weight gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

上記例示したように、EMIMAcはカルコンのα、β不飽和アルデヒドの正式な共役付加における触媒前駆体としての役割を果たす。例えば1-エチル-3-メチルイミダゾリウムクロリド（EMIMCl）及び1-ブチル-3-メチルイミダゾリウムクロリド（BMIMCl）などの他の市販のイミダゾリウムベースのイオン液体も調べたが、酢酸アニオンがあってもよいことを示すより低い収率で進行し、これらの...

Watch this Scientific Journal Video about Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

イオン液体によって媒介1,6-ケトエステルの高立体選択的合成：低分子ゲル化剤の新しいクラスへの迅速なアクセスを有効にする三成分の反応

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

highly-stereoselective-synthesis-16-ketoesters-mediated-ionic-liquids

Research

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Chemistry

8.7K ビュー.  Chalmers University of Technology. Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents. 

ビデオ: Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

Separation of Aldehydes and Reactive Ketones from Mixtures Using a Bisulfite Extraction Protocol

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer by generating a charged structure provides an opportunity to use extraction as a simple purification technique. By combining the use of a miscible organic solvent with saturated sodium bisulfite, aldehydes and reactive ketones can be successfully transformed into charged bisulfite adducts that can then be separated from other organic components of a mixture by the introduction of an immiscible organic layer. Here, we describe a simple protocol for the removal of aldehydes, including sterically-hindered neopentyl aldehydes and some ketones, from chemical mixtures. Ketones can be separated if they are sterically unhindered cyclic or methyl ketones. For aliphatic aldehydes and ketones, dimethylformamide is used as the miscible solvent to improve removal rates. The bisulfite addition reaction can be reversed by basification of the aqueous layer, allowing for the re-isolation of the reactive carbonyl component of a mixture.

Here, we present a protocol to remove aldehydes and reactive ketones from mixtures by a liquid-liquid extraction protocol directly with saturated sodium bisulfite in a miscible solvent. This combined protocol is rapid and facile to perform. The aldehyde or ketone can be re-isolated by the basification of the aqueous layer.

アルデヒドおよびケトン類の反応性の重亜硫酸塩の抽出のプロトコルを使用して混合物からの分離

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer ...

化学

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. Recently, we have developed a two-step strategy for ketone enolate umpolung that has enabled the development of methods for chlorination, azidation, and amination using azoles. In addition, we have developed C-C bond&#8211;forming arylation and allylation reactions. At the heart of these methods is the preparation of the intermediate and highly reactive enolonium species prior to addition of a reactive nucleophile. This strategy is thus reminiscent of the preparation and use of metal enolates in classical synthetic chemistry. This strategy allows the use of nucleophiles that would otherwise be incompatible with the strongly oxidizing hypervalent iodine reagents. In this paper we present a detailed protocol for chlorination, azidation, N-heteroarylation, arylation, and allylation. The products include motifs prevalent in medicinally active products. This article will greatly assist others in using these methods.

A two step one-pot protocol for the umpolung of ketone enolates to enolonium species and addition of a nucleophile to the &#945;-position is described. Nucleophiles include chloride, azide, azoles, allyl-silanes, and aromatic compounds.

Enolonium 種によるケトン類の極性転換を高機能化 2 段階のプロトコル

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. ...

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

We present the chemoselective synthesis of 1-(iodoethynyl)-4-methylbenzene, 1-(1,2-diiodovinyl)-4-methylbenzene, and 1-methyl-4-(1,2,2-triiodovinyl)benzene as representative examples for the practical chemoselective preparation of 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes from the chemoselective iodination of terminal alkynes mediated by hypervalent-iodine reagents. The chemoselectivity was confirmed by using p-tolylethyne as a model substrate to screen a variety of iodine sources and/or the hypervalent-iodine reagents. A combination of tetrabutylammonium iodide (TBAI) and (diacetoxyiodo)benzene (PIDA) selectively generates 1-iodoalkynes, while a combination of KI and PIDA generates 1,2-diiodoalkenes. A one-pot synthesis based on both TBAI-PIDA and KI-PIDA yields the corresponding 1,1,2-triiodoalkenes. These protocols were subsequently applied to the synthesis of synthetically important aromatic and aliphatic 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes, which were obtained in good yield with excellent chemoselectivity.

Herein, detailed protocols for the oxidative iodination of terminal alkynes using hypervalent-iodine reagents are presented, which chemoselectively afford 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes.

1-Iodoalkynes、1, 2-Diiodoalkenes、末端アルキンの酸化ヨウ素化に基づく 1,1,2 Triiodoalkenes の化学選択的準備

We present the chemoselective synthesis of 1-(iodoethynyl)-4-methylbenzene, 1-(1,2-diiodovinyl)-4-methylbenzene, and ...

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the reaction is commonly performed using chlorinated or amide solvent systems, which are hazardous to human health and the environment. Our methodology utilizes acetonitrile as a greener and less hazardous solvent system. This protocol exhibits rates and yields that are comparable to traditional solvent systems and employs an extraction and wash sequence that eliminates the need for the purification of the ester product via column chromatography. This general method can be used to couple a variety of carboxylic acids with 1&#176; and 2&#176; aliphatic alcohols, benzylic and allylic alcohols, and phenols to obtain pure esters in high yields. The goal of the protocol detailed here is to provide a greener alternative to a common esterification reaction, which could serve useful for ester synthesis in both academic and industrial applications.

A modified Steglich esterification reaction was used to synthesize a small library of ester derivatives with primary and secondary alcohols. The methodology uses a non-halogenated and greener solvent, acetonitrile, and enables product isolation in high yields without the need for chromatographic purification.

アセトニ トリル中で環境に優しい転移エステルを介してエステルの合成

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the ...

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of &#945;-Imino &#947;-Lactones and Alkylidene Pyrazolones

Bispirocyclic scaffolds are one of the important structural subunits in many natural products that exhibit diverse and attractive biological activities. Recently, we have developed an efficient organocatalytic strategy, which provides facile access to a variety of enantiomerically enriched bispiro[&#947;-butyrolactone-pyrrolidin-4,4&#39;-pyrazolone] skeletons. In this paper, we demonstrate a detailed protocol for the asymmetric synthesis of drug-like bispirocyclic compounds with two spirocyclic carbon centers via an organocatyltic 1,3-dipolar cycloaddition reaction. Spirocyclization synthons &#945;-imino &#947;-lactones and alkylidene pyrazolones are prepared first, which are then subjected to a cycloaddition reaction in the presence of a bifunctional squaramide organocatalyst to afford the desired bispirocycles in high yields and excellent stereoselectivities. Chiral high-performance liquid chromatography (HPLC) is carried out to determine the enantiomeric purity of the products, and the d.r. value is examined by proton nuclear magnetic resonance (1H NMR). The absolute configuration of the product is assigned according to an X-ray crystallographic analysis. This synthetic strategy allows scientists to prepare a diversity of bispirocyclic scaffolds in high yields and excellent diastereo- and enantioselectivities.

Enantiomerically enriched bispiro[&#947;-butyrolactone-pyrrolidin-4,4&#39;-pyrazolone] skeletons are asymmetrically synthesized through a simple organocatalytic 1,3-dipolar cycloaddition reaction.

効率的な薬物のような Bispirocyclic を介して α イミノ γ-ラクトンの有機触媒及び Alkylidene ピラゾロン足場の構築

Bispirocyclic scaffolds are one of the important structural subunits in many natural products that exhibit diverse and attractive biological activities. ...

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

The conjugate addition of organometallic reagents to &#945;,&#946;-unsaturated carbonyls represents an important method to generate C&#8211;C bonds in the preparation of all-carbon quaternary centers. Though conjugate additions of organometallic reagents are typically performed utilizing highly reactive organolithium or Grignard reagents, organozinc reagents have garnered attention for their enhanced chemoselectivity and mild reactivity. Despite numerous recent advances with more reactive diorganozinc and mixed diorganozinc reagents, the generation of all-carbon quaternary centers via the conjugate addition of functionalized monoorganozinc reagents remains a challenge. This protocol details a convenient and mild &#8220;one-pot&#8221; preparation and copper mediated conjugate addition of functionalized monoorganozinc bromides to cyclic &#945;,&#946;-unsaturated carbonyls to afford a broad scope of all-carbon quaternary centers in generally excellent yield and diastereoselectivity. Key to the development of this technology is the utilization of DMA as a reaction solvent with TMSCl as a Lewis acid. Notable advantages to this methodology include the operational simplicity of the organozinc reagent preparation afforded by the utilization of DMA as a solvent, as well as an efficient conjugate addition mediated by various Cu(I) and Cu(II) salts. Moreover, an intermediate silyl enol ether can be isolated utilizing a modified workup procedure. The substrate scope is limited to cyclic unsaturated ketones, and the conjugate addition is impeded by stabilized (e.g., allyl, enolate, homoenolate) and sterically encumbered (e.g., neopentyl, o-aryl) monoorganozinc reagents. Conjugate additions to five- and seven-membered rings were effective, albeit in lower yields compared with six-membered ring substrates.

A simple and practical protocol for the efficient conjugate addition of functionalized monoorganozinc bromides to cyclic &#945;,&#946;-unsaturated carbonyls to furnish all-carbon quaternary centers was developed.

官能化 Monoorganozinc 臭化物の共役添加による全炭素4級センターの効率的な合成

The conjugate addition of organometallic reagents to &#945;,&#946;-unsaturated carbonyls represents an important method to generate C&#8211;C bonds in the ...

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

CO2 transformations using a one-pot two-step method are presented herein. The purpose of the method is to give access to a variety of value-added products and notably to generate chiral carbon centers. The crucial first step consists in the selective double hydroboration of CO2 catalyzed by an iron hydride complex. The product obtained with this 4 e- reduction is a rare bis(boryl)acetal, compound 1, which is subjected in situ to three different reactions in a second step. The first reaction concerns a condensation reaction with (diisopropyl)phenylamine affording the corresponding imine 2. In the second and third reaction, intermediate 1 reacts with triazol-5-ylidene (Enders&#39; carbene) to afford compounds 3 or 4, depending on the reaction conditions. In both compounds, C-C bonds are formed, and chiral centers are generated from CO2 as the only source of carbon. Compound 4 exhibits two chiral centers obtained in a diastereoselective manner in a formose-type mechanism. We proved that the remaining boryl fragment plays a key role in this unprecedented stereocontrol. The interest of the method stands on the reactive and versatile nature of 1, giving rise to various complex molecules from a single intermediate. The complexity of a two-step method is compensated by the overall short reaction time (2 h for the larger reaction time), and mild reaction conditions (25 &#176;C to 80 &#176;C and 1 to 3 atm of CO2).

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

CO2 transformations are conducted in a one-pot two-step procedure for the synthesis of complex molecules. The selective 4 e- reduction of CO2 with a hydroborane reductant affords a reactive and versatile bis(boryl)acetal intermediate which is subsequently involved in condensation reaction or carbene-mediated C-C coupling generation.

多彩なCO2の複雑な製品への変革:ワンポット2段階戦略

CO2 transformations using a one-pot two-step method are presented herein. The purpose of the method is to give access to a variety of value-added products ...

Organocatalysis

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA
This experiment will demonstrate the concept of organocatalysis by illustrating the proper setup of a reaction that utilizes enamine catalysis. Organocatalysis is a form of catalysis that uses substoichiometric amounts of small organic molecules to accelerate reactions. This type of catalysis is complementary to other forms of catalysis such as transition metal or biocatalysis. Transition metal catalysis involves transition metals as catalysts and biocatalysis uses enzymes as catalysts. Some advantages of organocatalysis include the low toxicity and cost of the organocatalysts in comparison to many metal catalysts. In addition, most organocatalysts are not sensitive to air and moisture, unlike metal catalysts. In contrast to enzymes found in living organisms, the small molecules that act as organocatalysts are typically easy to access. Furthermore, organocatalysis offers complementary and new reactivity not observed with other forms of catalysis.

Organocatalysis: Principles and Applications

有機触媒反応

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA
This experiment will demonstrate the concept of ...

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有機化学Ⅱ

&alpha;-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview

The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an &#945;-hydroxy ketone product. The &#945;-hydroxy ketone is also called acyloin, so the reaction is referred to as &#8216;acyloin condensation.&#8217;
<img alt="Figure1" src="/files/ftp_upload/12908/12908_PT_Figure_1.svg" style="text-align: center; height: 65px;" />
In the acyloin condensation reaction, esters are converted to ketyls, which undergo radical dimerization to form an unstable tetrahedral intermediate. Further, this intermediate collapses to give a 1,2-diketone intermediate. The 1,2-diketones are comparatively more reactive than ketones towards electrophiles and reducing agents because of lower &#960;* energy. Consequently, two electrons sequentially transfer to the 1,2-diketone to form an enediolate. Lastly, the enediolate intermediate is quenched with acid to yield an &#945;-hydroxy ketone with a good yield.
Often some by-products are obtained alongside the major product because of the reactivity of nucleophilic enediolate. To overcome the side reactions and improve the yield of an acyloin, trimethylsilyl chloride is used to silylate the enediolate. This results in a bis-silyl ether, further hydrolyzed with aqueous acid to give &#945;-hydroxy ketones.

&amp;#945;-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview

エステルの還元的カップリングによるα-ヒドロキシケトン:アシロイン縮合の概要

The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester ...

JoVE Core

有機化学

ユニット １

ラジカル化学

KEY TERMS AND CONCEPTS

&alpha;-Alkylation of Ketones via Enolate Ions

Ketones with &alpha; protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the &#945; carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the &#945;&nbsp;carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction of the positive counterpart of the base with the anionic oxygen, which restricts the approaching electrophile, making the reaction less favorable. Also, the product obtained through C-attack is more stable than that obtained through O-&NoBreak;attack, as the stronger C=O &#960; bond is retained in the former, whereas a weaker C=C &#960; bond is preserved in the latter.
A subsequent reaction of the enolate with electrophiles such as alkyl halides produces an &#945;-alkylated ketone via the SN2 pathway. The &#945;-alkylation of ketones is achieved with the halides of primary alkyl, benzyl, and allylic groups. With secondary and tertiary alkyl halides, elimination predominates over substitution.

イオン液体によって媒介1,6-ケトエステルの高立体選択的合成：低分子ゲル化剤の新しいクラスへの迅速なアクセスを有効にする三成分の反応

要約

さらに動画を探す

この動画の章

アルデヒドおよびケトン類の反応性の重亜硫酸塩の抽出のプロトコルを使用して混合物からの分離

Enolonium 種によるケトン類の極性転換を高機能化 2 段階のプロトコル

1-Iodoalkynes、1, 2-Diiodoalkenes、末端アルキンの酸化ヨウ素化に基づく 1,1,2 Triiodoalkenes の化学選択的準備

アセトニトリル中で環境に優しい転移エステルを介してエステルの合成

効率的な薬物のような Bispirocyclic を介して α イミノ γ-ラクトンの有機触媒及び Alkylidene ピラゾロン足場の構築

官能化 Monoorganozinc 臭化物の共役添加による全炭素4級センターの効率的な合成

多彩_なCO2の複雑な製品への変革:ワンポット2段階戦略

有機触媒反応

エステルの還元的カップリングによるα-ヒドロキシケトン:アシロイン縮合の概要

エノラートイオンによるケトンのα-アルキル化

イオン液体によって媒介1,6-ケトエステルの高立体選択的合成：低分子ゲル化剤の新しいクラスへの迅速なアクセスを有効にする三成分の反応

要約

さらに動画を探す

この動画の章

アルデヒドおよびケトン類の反応性の重亜硫酸塩の抽出のプロトコルを使用して混合物からの分離

Enolonium 種によるケトン類の極性転換を高機能化 2 段階のプロトコル

1-Iodoalkynes、1, 2-Diiodoalkenes、末端アルキンの酸化ヨウ素化に基づく 1,1,2 Triiodoalkenes の化学選択的準備

アセトニ トリル中で環境に優しい転移エステルを介してエステルの合成

効率的な薬物のような Bispirocyclic を介して α イミノ γ-ラクトンの有機触媒及び Alkylidene ピラゾロン足場の構築

官能化 Monoorganozinc 臭化物の共役添加による全炭素4級センターの効率的な合成

多彩なCO2の複雑な製品への変革:ワンポット2段階戦略

有機触媒反応

エステルの還元的カップリングによるα-ヒドロキシケトン:アシロイン縮合の概要

エノラートイオンによるケトンのα-アルキル化

アセトニトリル中で環境に優しい転移エステルを介してエステルの合成

多彩_なCO2の複雑な製品への変革:ワンポット2段階戦略