Double bond isomerizations in unsaturated esters and enol ethers. I. Equilibrium studies in cyclic and acyclic systems

Rhoads, Sara Jane; CHATTOPADHYAY, J. K.; Waali, Edward E.

doi:10.1021/jo00835a036

Cited by 57 publications

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“…Conventional methods for the preparation of alkyl enol ethers involve the use of hard conditions such as strong bases (for example, n ‐butyllithium [ n ‐BuLi], lithium diisopropylamide [LDA], sodium hydride) in toxic organic solvents (e. g., tetrahydrofuran, dichloromethane) . However, it is also possible to synthesize alkyl enol ethers from aldehydes, by acetalization with an alcohol under acid catalysis, then removal of the alcohol, under acid or base catalysis . The elimination step is generally carried out with the use of aggressive Brønsted acids, such as sulfuric acid or p ‐toluenesulfonic acid or readily hydrolysable Lewis acids, such as aluminum .…”

Section: Reactivity Of Eco‐mn Catalystsmentioning

confidence: 99%

“…[50,56,57] However, it is also possible to synthesize alkyl enol ethers from aldehydes, by acetalization with an alcohol under acid catalysis, then removal of the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 alcohol, under acid or base catalysis. [58] The elimination step is generally carried out with the use of aggressive Brønsted acids, such as sulfuric acid or p-toluenesulfonic acid [58] or readily hydrolysable Lewis acids, such as aluminum. [59] This step can also be accomplished by co-catalysis with aluminum chloride and a non-nucleophilic base, such as triethylamine.…”

Section: Enol Ether Synthesismentioning

confidence: 99%

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Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

et al. 2020

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Phytoextraction is one of the most promising phytotechnologies used to restore natural environments degraded by mining activities. In New Caledonia, a few plant species, which belong to the Grevillea genus, have the ability to extract Mn from soil and accumulate it in abundance (over 1 % of leaves dry weight). This review describes the use of Grevillea Mn‐accumulating plant species to produce the first bio‐sourced Mn catalysts, called Eco‐Mn catalysts. Extensive structural studies of Eco‐Mn catalysts have highlighted an original composition characteristic of their vegetal origin. Eco‐Mn catalysts have demonstrated competitive catalytic activities compared to conventional Mn catalysts in Lewis acid catalysis, aminoreductions, alcohol oxidations, epoxidation reactions, oxidative cleavage of 1,2‐diols and alkenes and “Janus catalysts” for sequential tandem oxidations such as tandem carbonyl‐ene cyclisation, synthesis of substituted pyridines and oxidative iodination of ketones.

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Section: Reactivity Of Eco‐mn Catalystsmentioning

confidence: 99%

Section: Enol Ether Synthesismentioning

confidence: 99%

Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

et al. 2020

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“…tetrahydrofuran, dichloromethane) (Earnshaw et al 1979;Gassman et al 1993;Russell and Hegedus 1983). However, it is also possible to synthesize alkyl enol ethers 3 starting from aldehydes 1, by acetalization with an alcohol under acid catalysis, then elimination of alcohol, under acid or basic catalysis (Rhoads et al 1970). The elimination step is usually conducted under aggressive Brønsted acids, such as sulfuric acid or p-toluenesulfonic acid (Rhoads et al 1970) or readily hydrolysable Lewis acids such as aluminum chloride (Barbot and Miginiac 1979).…”

Section: Lewis/brønsted Acid Catalysis With Eco-mnmentioning

confidence: 99%

“…However, it is also possible to synthesize alkyl enol ethers 3 starting from aldehydes 1, by acetalization with an alcohol under acid catalysis, then elimination of alcohol, under acid or basic catalysis (Rhoads et al 1970). The elimination step is usually conducted under aggressive Brønsted acids, such as sulfuric acid or p-toluenesulfonic acid (Rhoads et al 1970) or readily hydrolysable Lewis acids such as aluminum chloride (Barbot and Miginiac 1979). This step can also be accomplished under co-catalysis with aluminum chloride and a non-nucleophilic base, such as triethylamine (Barbot and Miginiac 1979).…”

Section: Lewis/brønsted Acid Catalysis With Eco-mnmentioning

confidence: 99%

Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants

Escande

Renard

Grison

2014

Environ Sci Pollut Res

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Among the phytotechnologies used for the reclamation of degraded mining sites, phytoextraction aims to diminish the concentration of polluting elements in contaminated soils. However, the biomass resulting from the phytoextraction processes (highly enriched in polluting elements) is too often considered as a problematic waste. The manganese-enriched biomass derived from native Mn-hyperaccumulating plants of New Caledonia was presented here as a valuable source of metallic elements of high interest in chemical catalysis. The preparation of the catalyst Eco-Mn1 and reagent Eco-Mn2 derived from Grevillea exul exul and Grevillea exul rubiginosa was investigated. Their unusual polymetallic compositions allowed to explore new reactivity of low oxidative state of manganese-Mn(II) for Eco-Mn1 and Mn(IV) for Eco-Mn2. Eco-Mn1 was used as a Lewis acid to catalyze the acetalization/elimination of aldehydes into enol ethers with high yields; a new green and stereoselective synthesis of (-)-isopulegol via the carbonyl-ene cyclization of (+)-citronellal was also performed with Eco-Mn1. Eco-Mn2 was used as a mild oxidative reagent and controlled the oxidation of aliphatic alcohols into aldehydes with quantitative yields. Oxidative cleavage was interestingly noticed when Eco-Mn2 was used in the presence of a polyol. Eco-Mn2 allowed direct oxidative iodination of ketones without using iodine, which is strongly discouraged by new environmental legislations. Finally, the combination of the properties in the Eco-Mn catalysts and reagents gave them an unprecedented potential to perform sequential tandem oxidation processes through new green syntheses of p-cymene from (-)-isopulegol and (+)-citronellal; and a new green synthesis of functionalized pyridines by in situ oxidation of 1,4-dihydropyridines.

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“…[143] Nach Aufarbeitung erhielt man das eingesetzte Edukt. dener Enolether mit Quecksilber-(II)-acetat [144] und Natriummethanolat [145] beschrieben. rein thermischen Umsetzung [82] unter erhöhten Temperaturen wurde nur Zersetzung beobachtet (Eintrag 1), bei niedrigeren Temperaturen konnte, auch nach längerer Reaktionszeit, ausschließlich Edukt nachgewiesen werden (Eintrag 2).…”

Section: Ii521 Durchführung Der Syntheseunclassified

Synthese und Anwendung eines radioaktiven Photoaffinitätslabels zur Wirkortbestimmung von Naturstoffen sowie Beiträge zur Totalsynthese des Collinolactons

Bender¹

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Für die Untersuchung der Wechselwirkungen kleiner bioaktiver Moleküle mit Proteinen stehen mehrere Strategien zur Verfügung (Abbildung 1). [4] Sind das Zielprotein und der Wirkstoff in ausreichenden Mengen vorhanden, so bieten 3D-Strukturaufklärungsmethoden wie NMR-Untersuchungen oder zum Beispiel (Co)-Kristallstrukturen von Wirkstoff und Protein einen direkten Zugang zu den dreidimensionalen Strukturen der Zielproteine auf atomarem Level. Bei der Strukturaufklärung mittels genetischer Methoden werden durch Deletionen oder Mutationen die natürlichen Strukturen der Proteine verändert. In Abhängigkeit von den Auswirkungen auf die Wirksamkeit der Moleküle kann auf die Struktur der Bindungstasche geschlossen werden. Chemische Methoden hingegen ermöglichen die direkte Identifizierung von Zielproteinen in Proteingemischen durch das affinitätsbasierte Einbringen eines Tags in die Proteinstruktur. Ein Beispiel ist das Visualisieren von Biomolekülen mit Hilfe eines Fluorophors in Zellkompartimenten. A.1.1 Zum Prinzip des PhotoaffinitätslabelingsDas Prinzip der Photoaffinitätsmarkierung wurde erstmals 1962 von Westheimer und Mitarbeitern [5] beschrieben und hat seitdem breite Anwendung gefunden. [6a] In Abb. 2 ist eine schematische Darstellung des Verlaufs einer Photoaffinitäts-markierung wiedergegeben. Ein biologisch aktiver Ligand, welcher mit einer photoaktivierbaren Spezies (hier eine Diazirinylbenzoesäure) versehen ist, wird zum Target (einem beliebigen Protein) gegeben. Nach Bildung des Target-Ligand-Komplexes wird durch Bestrahlen mit Licht einer bestimmten Wellenlänge aus dem Photoaffinitätslabel die aktive Spezies (Carbene, Nitrene etc.) freigesetzt, welche unverzüglich mit umliegenden Aminosäuren

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Double bond isomerizations in unsaturated esters and enol ethers. I. Equilibrium studies in cyclic and acyclic systems

Abstract: tralized with dilute H2S04. The ether layer was washed with water, dried (MgS04), and evaporated to give 1.0 g (65%) of the hydroxymethyl derivative 11, mp 175-176°.

Cited by 57 publications

References 0 publications

Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants

Synthese und Anwendung eines radioaktiven Photoaffinitätslabels zur Wirkortbestimmung von Naturstoffen sowie Beiträge zur Totalsynthese des Collinolactons

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