Trimeric Cinchona alkaloid phase-transfer catalyst: α,α′,α′′-tris[O(9)-allylcinchonidinium]mesitylene tribromide

Park, Hyeung‐geun; Jeong, Byeong‐Seon; Yoo, Mi‐Sook; Park, Mi‐kyoung; Huh, Hoon; Jew, Sang‐sup

doi:10.1016/s0040-4039(01)00809-7

Cited by 103 publications

(26 citation statements)

References 25 publications

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“…When achiral tetrabutylammonium bromide was used as the catalyst, roughly the same diastereoselectivity was observed as with the cinchonidine and cinchonine catalysts 113 and 114 , respectively. To enhance the catalyst activity, bis‐206 and triscinchona207 derivatives were prepared and tested (Figure 11). 7b, 208…”

Section: Enantioselective Phase‐transfer Reactions195mentioning

confidence: 99%

In the Golden Age of Organocatalysis

2004

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The term "organocatalysis" describes the acceleration of chemical reactions through the addition of a substoichiometric quantity of an organic compound. The interest in this field has increased spectacularly in the last few years as result of both the novelty of the concept and, more importantly, the fact that the efficiency and selectivity of many organocatalytic reactions meet the standards of established organic reactions. Organocatalytic reactions are becoming powerful tools in the construction of complex molecular skeletons. The diverse examples show that in recent years organocatalysis has developed within organic chemistry into its own subdiscipline, whose "Golden Age" has already dawned.

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Section: Enantioselective Phase‐transfer Reactions195mentioning

confidence: 99%

In the Golden Age of Organocatalysis

2004

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“…Thus, the advent in the early 1990 s of the enantioselective alkylation of amino acid imines under PTC conditions catalyzed by quaternized Cinchona alkaloids, [3] pioneered by ODonnell [4] and improved by Corey [5] and Lygo, [6] allowed one to obtain impressive degrees of enantioselection using a very simple procedure. Moreover, dimeric, [7] trimeric [8] and even dendrimeric [9] Cinchona alkaloid-derived catalysts, as well as non-Cinchona-derived species such as spiro ammonium [10] and phosphonium salts, [11] TAD-DOL [12a, b] and other tartaric derivatives, [12c, d] guanidinium salts, [12e] binaphthyl-derived amines [12b,13] and salenmetal complexes [14] have also been used in this kind of asymmetric PTC alkylations.…”

Section: Introductionmentioning

confidence: 99%

Polystyrene‐Anchored Cinchona Ammonium Salts: Easily Recoverable Phase‐Transfer Catalysts for the Asymmetric Synthesis of α‐Amino Acids

2004

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Cinchonidine, epicinchonidine, cinchonine or quinine have been N-anchored to cross-linked polystyrene (Merrifield resin) or grafted polystyrene (SynPhase TM Lanterns) affording polymer-supported chiral ammonium salts which are employed as phasetransfer catalysts in the asymmetric alkylation of N-(diphenylmethylene)glycine esters. These new polymeric catalysts can be easily recovered after the reaction by simple filtration and reused.

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“…Interestingly, an opposite sense of the asymmetric induction can be observed changing the alkaloid moiety from cinchonidine [(S)-enantioselectivity] to its so-called pseudoenantiomer cinchonine [(R)-enantioselectivity] [7]. Moreover, dimeric [8], trimeric [9] and even dendrimeric Attaching the chiral catalyst to a solid support can be considered a next step in the development of the PTC methodology due to the resulting ease of separation and possible recycling. As a result, the preparation and uses of all kind of supported reagents is considered nowadays a fast developing topic [16].…”

Section: Introductionmentioning

confidence: 99%

Polymer-Supported Cinchona Alkaloid-Derived Ammonium Salts as Recoverable Phase-Transfer Catalysts for the Asymmetric Synthesis of α-Amino Acids

2004

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Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee's were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed.

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Trimeric Cinchona alkaloid phase-transfer catalyst: α,α′,α′′-tris[O(9)-allylcinchonidinium]mesitylene tribromide

Cited by 103 publications

References 25 publications

In the Golden Age of Organocatalysis

In the Golden Age of Organocatalysis

Polystyrene‐Anchored Cinchona Ammonium Salts: Easily Recoverable Phase‐Transfer Catalysts for the Asymmetric Synthesis of α‐Amino Acids

Polymer-Supported Cinchona Alkaloid-Derived Ammonium Salts as Recoverable Phase-Transfer Catalysts for the Asymmetric Synthesis of α-Amino Acids

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