Name: 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
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1. gramskala syntes av metyl 6-oxo-3,4,6-triphenylhexanoate <ol><li> Torr 1-etyl-3-metyl imidazolium acetat (EMIMAc) i en rundbottnad kolv på en rotationsindunstare vid 10 mbar, 40 ° C under 1 timme. </li><li> Lägg 2,1 g torr EMIMAc och 1,0 g 1,3-difenyl-2-propen-1-en till en 100 ml rundbottnad kolv utrustad med en magnetisk omrörare. </li><li> Lägg 2.019 ml metanol och 2,3 g kanelaldehyd till kolven. </li><li> Vid rumstemperatur (22 ° C) lösa upp blandningen i 60 ml diklormetan genom omrörning under 1 minut. ...

<ol>
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Baserat på den anti-konfiguration bestäms av röntgenanalys av ketoester 3 och den mekanistiska utredning föreslagits av Bode och medarbetare 30 följande reaktionsvägen föreslås (Figur 5). Deprotonering av IL genererar NHC arter; NHC reagerar med den omättade aldehyden för att bilda den Breslow mellanliggande I. Breslow mellanliggande och chalkon reagerar i en tvär bensoin reaktion för att bilda dien II. Mellan II genomgår en oxy-Cope ombildning via båt övergångstillst...

<img alt="TOC 1" src="/files/ftp_upload/53213/53213TOC.jpg" /> (Ovan) Tre-komponent syntes av 1,6-ketoestrar: en ny klass av lågmolekylära gelators. Joniska vätskor (ILS) har hög stabilitet, låg flyktighet, obrännbarhet och har därför gjorts uppmärksamhet som säkra reaktionsmedier och ideala lösningsmedel för återvinning. 1-3 dialkyl imidazoliums är en viss typ av joniska vätskor som, i närvaro av en bas , kan deprotoneras att göra en N-heterocykliska carbene (NHC). 4 När det gäller organocatalysis, NHCs, arbetar under olika reaktionsvägar, har funnit utbredd användning i ett brett spektrum av generiska reaktioner. 5-11 Trots detta, anslutningen mellan ILS och CC bindning forming NHC-katalys är relativt outforskat. Ändå NHCs härledd från ILS har rapporterats katalysera CC bindningsbildande reaktioner, såsom bensoin kondensation och Stetter-reaktionen. 12-22 Exempelvis Davis et al. Har visat att ILS härledda från N-alkyl thiazoliums tjäna som precatalysts i bildandet av bensoin från bensaldehyd. 12 På senare tid, Chen och medarbetare utökat detta koncept med hjälp av en imidazolium baserad IL, 1-etyl-3-metyl imidazolium acetat (EMIMAc), att utföra bensoin kondens på 5-hydroximetylfurfural (HMF) för att generera 5,5 &quot;-di (hydroximetyl) Furoin (DHMF). 23 Eftersom ILS är kommersiellt tillgängliga och erbjuder ett billigt sätt att generera NHCs, var vi intresserade av att undersöka vad andra typer av reaktioner ILS kunde utföra. För detta ändamål har vi funnit att dialkyl imidazoliums effektivt skulle kunna användas som precatalysts i det formella konjugatet additipå omättade aldehyder till chalkoner (Figur 1), vilket gav 1,6-ketoestrar. Det mest effektiva IL, EMIMAc, främjar en mycket stereoselektiv reaktion mellan kanelaldehyd och chalkon. Reaktionen sker med hög preferens för anti -diastereomeren och de 1,6-ketoestrar kan isoleras i utbyten på upp till 92%. 24,25,26 <img alt="Figur 1" src="/files/ftp_upload/53213/53213fig1.jpg" /> Figur 1: IL-medierad tre-komponent, stereo tillsats av kanelaldehyd till chalkon.

<table>
	<tbody>
		<tr>
			<td>1-ethyl-3-methyl imidazolium acetate</td>
			<td>Aldrich</td>
			<td>51053-100G-F</td>
			<td>Produced by BASF &#8805;90%, dried on a rotary evaporated before use (10 mBar, 40 &#176;C, 1h) 
			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% 
			CAS NUMBER: 94-41-7</td>
		</tr>
		<tr>
			<td>trans-cinnamaldehyde&#160;</td>
			<td>Aldrich</td>
			<td>C80687-25G</td>
			<td>99%, stored under nitrogen prior to use 
			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% 
			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. &#8805;99.8% (GC) 
			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 
			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 
			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.

Såsom exemplifierats ovan, EMIMAc tjäna som en förkatalysator i den formella konjugataddition av α, β-omättad aldehyd till chalkoner. Andra kommersiellt tillgängliga imidazoliumsalter baserade ILS såsom en-etyl-3-metylimidazolium-klorid (EMIMCl) och 1-butyl-3-metylimidazolium-klorid (BMIMCl) undersöktes också, emellertid, dessa reaktioner fortskred i lägre utbyten, vilket indikerar att acetatanjon kan vara viktigt med avseende på reaktivitet (tabell 1, post 1-3). 27,28 ...

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.

Mycket stereoselektiv syntes av 1,6-ketoestrar medierad av joniska lösningar: En tre-komponent Reaktion möjliggör snabb tillgång till en ny klass av lågmolekylära 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 ...

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Beredning och användning av samariumdijodid (SMI<sub&gt; 2</sub&gt;) I Organic Synthesis: den mekanistiska roll HMPA och Ni (II) salter i Samarium Barbier Reaktion

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Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Från molekyler till material: iscensätta nya Joniska flytande kristaller genom Halogen Bonding

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Tillverkning och provning av katalytisk Aerogel redo Via snabba Överkritisk extraktion

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

Snabb Nanoprobe Signal förbättring genom In Situ guld nanopartiklar syntes

The use of nanoprobes such as gold, silver, silica or iron-oxide nanoparticles as detection reagents in bioanalytical assays can enable high sensitivity ...