Synthesis of (αR,βS)-epoxyketones by asymmetric epoxidation of chalcones with cinchona phase-transfer catalysts

Yoo, Mi‐Sook; Kim, Dong-Guk; Ha, Min Woo; Jew, Sang‐sup; Park, Hyeung‐geun; Jeong, Byeong‐Seon

doi:10.1016/j.tetlet.2010.08.056

Cited by 28 publications

(7 citation statements)

References 31 publications

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“…[136] A highly enantioselective epoxidation of chalcones catalyzed by 1 t was reported by Park, Jeong, and co-workers. [137] Hori et al designed the phase-transfer catalyst (S,S)-167 containing a quaternary ammonium salt moiety and a crown ether moiety. [138] The ability of the catalyst was demonstrated in the asymmetric epoxidation of a,b-unsaturated ketones, with the epoxides being obtained with moderate enantioselectivity.…”

Section: Epoxidationmentioning

confidence: 99%

Recent Developments in Asymmetric Phase‐Transfer Reactions

2013

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Phase-transfer catalysis has been recognized as a powerful method for establishing practical protocols for organic synthesis, because it offers several advantages, such as operational simplicity, mild reaction conditions, suitability for large-scale synthesis, and the environmentally benign nature of the reaction system. Since the pioneering studies on highly enantioselective alkylations promoted by chiral phase-transfer catalysts, this research field has served as an attractive area for the pursuit of "green" sustainable chemistry. A wide variety of asymmetric transformations catalyzed by chiral onium salts and crown ethers have been developed for the synthesis of valuable organic compounds in the past several decades, especially in recent years.

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Section: Epoxidationmentioning

confidence: 99%

Recent Developments in Asymmetric Phase‐Transfer Reactions

2013

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“…In addition the use of this catalyst was also investigated for the asymmetric epoxidation of chalcone 23 , thus employing an achiral nucleophile and a prochiral electrophile (Scheme 6, lower reaction scheme). 29 Unfortunately, despite a thorough screening of different reaction conditions it was not possible to obtain the epoxide 24 in any reasonable enantiomeric excess although the catalyst promoted the reaction well giving the product in high yield. 30…”

Section: Azepane 5-based Phase-transfer Catalystsmentioning

confidence: 99%

Investigations Concerning the Syntheses of TADDOL-Derived Secondary Amines and Their Use To Access Novel Chiral Organocatalysts

Gratzer

Waser

2012

Synthesis

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Abstract:A structurally carefully diversified library of novel TADDOL-derived chiral secondary amines was synthesized and investigated for their applicability to obtain new organocatalysts like chiral Lewis bases and chiral phase-transfer catalysts. The scope and limitations of the developed syntheses routes to access these catalysts as well their catalytic performance in different benchmark reactions were systematically investigated. The most powerful of the catalysts prepared was found to be highly useful for the phasetransfer catalyzed α-alkylation of glycine Schiff base (high yields and up to 93% ee).Key words: chiral pool, tartaric acid, asymmetric phase-transfer catalysis, Lewis base catalysis, asymmetric alkylationThe use of chiral small molecule organocatalysts to facilitate demanding stereoselective applications has attracted considerable interest over the last decade.

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“…[65] Es wurde auch gezeigt, dass von Cinchonin abgeleitete quartäre Salze wirksame Katalysatoren der enantioselektiven Epoxidierung von 1,3-Diarylenonen sind. [68] Die asymmetrische Epoxidierung von a,b-ungesättigten Ketonen mittels PTC konnte durch die Entwicklung verschiedener anderer Ammoniumsalzkatalysatoren weiter ausgedehnt werden. [66] Von den untersuchten elektronenziehenden Gruppen lieferte das 4-Iodbenzyl-Derivat 62 die besten Ergebnisse (Schema 22, Bedingungen E).…”

Section: Methodsunclassified

“…[66b] In einem anderen Beispiel eines von Cinchonin abgeleiteten Katalysators mit einer elektronenziehenden Benzylgruppe wurde gefunden, dass der Trifluorbenzyl-Cinchona-Katalysator 63 bei 1,3-Diarylenonen zu mittleren bis hohen Ausbeuten und Enantioselektivitäten führt (Bedingungen F). [68] Die asymmetrische Epoxidierung von a,b-ungesättigten Ketonen mittels PTC konnte durch die Entwicklung verschiedener anderer Ammoniumsalzkatalysatoren weiter ausgedehnt werden. Das C 2 -symmetrische, tetracyclische Guanidiniumsalz 64 führte bei zwei Chalkonen zu hohen Enantioselektivitäten, die Ausbeuten wurden allerdings nicht verçffentlicht (Schema 22, Bedingungen G).…”

Section: Methodsunclassified

Organokatalytische asymmetrische Epoxidierungen – Reaktionen, Mechanismen und Anwendungen

Davis¹,

Stiller²,

Naicker³

et al. 2014

Angewandte Chemie

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Chirale Epoxide sind vielseitige Bausteine in der Synthese komplexer organischer Gerüste. Durch die hohe Spannung ihres dreigliedrigen Rings können Epoxide eine Reihe von nucleophilen Ringöffnungsreaktionen eingehen. Nach der Entwicklung der Sharpless‐Epoxidierung folgten zahlreiche wichtige Fortschritte, und das rasch aufstrebende Feld der asymmetrischen Organokatalyse stellt nun Katalysatoren für die Epoxidierung eines breiten Spektrums an ungesättigten Carbonylverbindungen bereit. In diesem Kurzaufsatz sind jüngste Entwicklungen auf dem Gebiet organokatalytischer asymmetrischer Epoxidierungen zusammengefasst. Die vorgeschlagenen Reaktionsmechanismen werden beschrieben, und Anwendungen werden beschrieben.

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Synthesis of (αR,βS)-epoxyketones by asymmetric epoxidation of chalcones with cinchona phase-transfer catalysts

Cited by 28 publications

References 31 publications

Recent Developments in Asymmetric Phase‐Transfer Reactions

Recent Developments in Asymmetric Phase‐Transfer Reactions

Investigations Concerning the Syntheses of TADDOL-Derived Secondary Amines and Their Use To Access Novel Chiral Organocatalysts

Organokatalytische asymmetrische Epoxidierungen – Reaktionen, Mechanismen und Anwendungen

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