C3 Symmetry in Asymmetric Catalysis and Chiral Recognition

Moberg, Christina

doi:10.1002/(sici)1521-3773(19980216)37:3<248::aid-anie248>3.0.co;2-5

Cited by 246 publications

(35 citation statements)

References 132 publications

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“…The importance of the C 3 symmetry in chiral recognition has been pointed out [555]. Apart from Kubiks cyclo-hexapeptide ( 233 ) and the example 176 from Ahn et al previously noted, there are only a few examples of enantioselective receptors for chiral ammonium ions with C 3 symmetry [554,568–571].…”

Section: Reviewmentioning

confidence: 99%

Molecular recognition of organic ammonium ions in solution using synthetic receptors

Späth¹,

König²

2010

Beilstein J. Org. Chem.

219

130

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SummaryAmmonium ions are ubiquitous in chemistry and molecular biology. Considerable efforts have been undertaken to develop synthetic receptors for their selective molecular recognition. The type of host compounds for organic ammonium ion binding span a wide range from crown ethers to calixarenes to metal complexes. Typical intermolecular interactions are hydrogen bonds, electrostatic and cation–π interactions, hydrophobic interactions or reversible covalent bond formation. In this review we discuss the different classes of synthetic receptors for organic ammonium ion recognition and illustrate the scope and limitations of each class with selected examples from the recent literature. The molecular recognition of ammonium ions in amino acids is included and the enantioselective binding of chiral ammonium ions by synthetic receptors is also covered. In our conclusion we compare the strengths and weaknesses of the different types of ammonium ion receptors which may help to select the best approach for specific applications.

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Section: Reviewmentioning

confidence: 99%

Molecular recognition of organic ammonium ions in solution using synthetic receptors

Späth¹,

König²

2010

Beilstein J. Org. Chem.

219

130

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“…The advantages of C 2 -symmetric catalysts have been widely described in the literature, e.g., enhanced rigidity of molecule and the same chiral environment, which may reduce the number of possible transition states [ 131 , 132 , 133 , 134 ]. The Vega-Pérez and Iglesias-Guerra teams prepared the C 2 -symmetric organocatalyst 249 ( Scheme 67 ), which consisted of two functionalized d -glucose units 1,3-linked to an acetone moiety.…”

Section: Sugar Ketonesmentioning

confidence: 99%

Synthesis and Applications of Carbohydrate-Based Organocatalysts

et al. 2021

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Organocatalysis is a very useful tool for the asymmetric synthesis of biologically or pharmacologically active compounds because it avoids the use of noxious metals, which are difficult to eliminate from the target products. Moreover, in many cases, the organocatalysed reactions can be performed in benign solvents and do not require anhydrous conditions. It is well-known that most of the above-mentioned reactions are promoted by a simple aminoacid, l-proline, or, to a lesser extent, by the more complex cinchona alkaloids. However, during the past three decades, other enantiopure natural compounds, the carbohydrates, have been employed as organocatalysts. In the present exhaustive review, the detailed preparation of all the sugar-based organocatalysts as well as their catalytic properties are described.

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“…As the preparation of enantiopure organic compounds is of great interest, asymmetric catalysis has developed into a dynamic, rapidly evolving field [2]. Compounds with rotational symmetry have gained increased attention in asymmetric synthesis because they are believed to be able to improve enantioselectivity by decreasing the number of possible transition states during the reaction [3][4][5]. Due to their beneficial effect on enantioselectivity, C 2 -and C 3 -symmetric molecules have been the focus of extensive research and, as a result, C 3 -symmetric compounds have been successfully applied as catalysts, ligands, molecular receptors, supra-and macromolecular constructs, gelators, metal-organic materials (MOMs), etc.…”

Section: Introductionmentioning

confidence: 99%

“…SolventReaction Time (h) Yield (13, %) 2Enantiomeric Excess [(S), %]Solvent Reaction Time (h) Yield (13, %)2 Enantiomeric Excess [(S), %]3 …”

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confidence: 99%

Synthesis of C3-Symmetric Cinchona-Based Organocatalysts and Their Applications in Asymmetric Michael and Friedel–Crafts Reactions

et al. 2021

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In this work, anchoring of cinchona derivatives to trifunctional cores (hub approach) was demonstrated to obtain size-enlarged organocatalysts. By modifying the cinchona skeleton in different positions, we prepared four C3-symmetric size-enlarged cinchona derivatives (hub-cinchonas), which were tested as organocatalysts and their catalytic activities were compared with the parent cinchona (hydroquinine) catalyst. We showed that in the hydroxyalkylation reaction of indole, hydroquinine provides good enantioselectivities (up to 73% ee), while the four new size-enlarged derivatives resulted in significantly lower values (up to 29% ee) in this reaction. Anchoring cinchonas to trifunctional cores was found to facilitate nanofiltration-supported catalyst recovery using the PolarClean alternative solvent. The C3-symmetric size-enlarged organocatalysts were completely rejected by all the applied membranes, whereas the separation of hydroquinine was found to be insufficient when using organic solvent nanofiltration. Furthermore, the asymmetric catalysis was successfully demonstrated in the case of the Michael reaction of 1,3-diketones and trans-β-nitrostyrene using Hub3-cinchona (up to 96% ee) as a result of the positive effect of the C3-symmetric structure using a bulkier substrate. This equates to an increased selectivity of the catalyst in comparison to hydroquinine in the latter Michael reaction.

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C3 Symmetry in Asymmetric Catalysis and Chiral Recognition

Abstract: Rotational symmetry can be an important factor in the design of highly selective receptors for chiral recognition. This is well known for C -symmetric compounds, but the concept can be extended to chiral compounds of higher symmetry such as 1.

Cited by 246 publications

References 132 publications

Molecular recognition of organic ammonium ions in solution using synthetic receptors

Molecular recognition of organic ammonium ions in solution using synthetic receptors

Synthesis and Applications of Carbohydrate-Based Organocatalysts

Synthesis of C3-Symmetric Cinchona-Based Organocatalysts and Their Applications in Asymmetric Michael and Friedel–Crafts Reactions

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