Polymeric chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of α-amino acids

Lee, Jeong-Hee; Yoo, Mi‐Sook; Jung, Ji‐Hee; Jew, Sang‐sup; Park, Hyeung‐geun; Jeong, Byeong‐Seon

doi:10.1016/j.tet.2007.05.076

Cited by 62 publications

(32 citation statements)

References 63 publications

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“…[6] Park and co-workers summarized the effect of a series of dimeric and trimeric quaternary ammonium salts of type 9 derived from cinchona alkaloids on the asymmetric alkylation of 7 (Scheme 4). [7] The dimeric catalyst 9 a was found to be one of the most effective catalysts for the reaction.…”

Section: Alkylationmentioning

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: Alkylationmentioning

confidence: 99%

Recent Developments in Asymmetric Phase‐Transfer Reactions

2013

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“…[14] However, to the best of our knowledge, the activity of our dendrimers compared with supported cinchonine alkaloid in polymers (even in SynPhase TM lanterns) are higher in ee, and in addition, the reaction time has been reduced, from several hours to one, in our case at 0 ºC, using only 0.1 mol% of our catalyst (1.2 mol% of cinchonine moieties). [18,19,30] The possibility of the existence of a collaborative effect among the cinchonine moieties on the surface of the dendrimer could be the explanation of this kinetic improvement, showing a positive dendritic effect. This effect does not exist when Cinchone derivatives are incorporated at the core of a dendrimer.…”

Section: Scheme 2 Preparation Of Dendrimeric Phase Transfer Catalystmentioning

confidence: 99%

Recoverable Dendritic Phase‐Transfer Catalysts that Contain (+)‐Cinchonine‐Derived Ammonium Salts

et al. 2016

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ABSTRACT:Four new phosphorus dendrimeric phase-transfer catalysts are prepared containing on the surface twelve (+)-cinchoninium salts, obtained by quaternisation of the quinuclidinic nitrogen. Asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, showing that the more active dendrimeric catalyst is the one containing an allyl group on the O-9 hydroxy group of the cinchonine units. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and slight decrease in enantioselectivity. When other electrophiles are used, substituted benzyl bromides give better results than other activated alkyl bromides affording the corresponding (R)-amino acids derivatives. Comparison of these results with the ones previously reported for similar cinchoninium salts, shows that dendrimers could be a better support than other polymers for this type of organocatalysis.

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“…[6] Park et al beschrieben die Wirkung einer Reihe dimerer und trimerer, von Cinchona-Alkaloiden abgeleiteter quartä-rer Ammoniumsalze des Typs 9 auf die asymmetrische Alkylierung von 7 (Schema 4). [7] Dabei war die dimere Verbindung 9 a einer der wirksamsten Katalysatoren für die Reaktion.…”

Section: Asymmetrische Synthese Von A-aminosäurenunclassified

Neue Entwicklungen bei asymmetrischen Phasentransferreaktionen

2013

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Die Phasentransferkatalyse bildet eine effiziente Grundlage zur Einführung praktischer Methoden in die organische Synthese, denn sie bietet mehrere Vorteile wie einfache Handhabung, milde Reaktionsbedingungen, die Eignung für großtechnische Synthesen und ein umweltfreundliches Reaktionssystem. Seit den wegweisenden Arbeiten zu hoch enantioselektiven Alkylierungen mit chiralen Phasentransferkatalysatoren ist dieses Forschungsgebiet im Hinblick auf eine umweltverträgliche, nachhaltige Chemie von Interesse, und in den vergangenen Jahrzehnten, vor allem in den letzten Jahren, wurden zahlreiche asymmetrische, durch chirale Oniumsalze und Kronenether katalysierte Umwandlungen für die Synthese wertvoller organischer Verbindungen entwickelt.

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Polymeric chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of α-amino acids

Cited by 62 publications

References 63 publications

Recent Developments in Asymmetric Phase‐Transfer Reactions

Recent Developments in Asymmetric Phase‐Transfer Reactions

Recoverable Dendritic Phase‐Transfer Catalysts that Contain (+)‐Cinchonine‐Derived Ammonium Salts

Neue Entwicklungen bei asymmetrischen Phasentransferreaktionen

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