Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

Scharwächter, Klaus; Hochmuth, Detlev H.; Dittmann, Helmutt; König, Wilfried Α.

doi:10.1002/chir.10024

Cited by 22 publications

(9 citation statements)

References 42 publications

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“…Research by Kanomata has similarly reported the synthesis of enantiomeric cyclophanes with 10 and 11 carbons isolable at room temperature [13]. Quantitatively similar results have also been found with 1,n-dioxa[n]paracyclophanes and 1,n-diaza[n]paracyclophanes [14,15]. Whether similar tether lengths will yield comparably isolable atropisomers at room temperature for diarylethyl cyclophanes remains unknown and is the point of this investigation.…”

Section: Introductionsupporting

confidence: 52%

Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

et al. 2021

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The restricted rotation of chemical bonds may lead to the formation of stable, conformationally chiral molecules. While the asymmetry in chiral molecules is generally observed in the presence of one or more stereocenters, asymmetry exhibited by conformational chirality in compounds lacking stereocenters, called atropisomerism, depends on structural and temperature factors that are still not fully understood. This atropisomerism is observed in natural diarylether heptanoids where the length of the intramolecular tether constrains the compounds to isolable enantiomers at room temperature. In this work, we examine the impact tether length has on the activation free energies to isomerization of a diarylether cyclophane substructure with a tether ranging from 6 to 14 carbons. Racemization activation energies are observed to decay from 48 kcal/mol for a 7-carbon tether to 9.2 kcal/mol for a 14-carbon tether. Synthetic efforts to experimentally test these constraints are also presented. This work will likely guide the design and synthesis of novel asymmetric cyclophanes that will be of interest in the catalysis community given the importance of atropisomeric ligands in the field of asymmetric catalysis.

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Section: Introductionsupporting

confidence: 52%

Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

et al. 2021

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“…In continuation of these studies, Scharwächter et al [150] investigated a number of atropisomeric 1,n-diaza [n]paracyclophanes 32 (n 5 10-12; X 5 H, CH 3 , CF 3 , Cl, Br, NO 2 , and F). Enantiomerization barriers between 111.2 and 126.1 kJ/mol, which depend on the bulkiness of the substituent X (NO 2 )CF 3 4Br4Cl4CH 3 EF), could be determined demonstrating the great potential of sfCE.…”

Section: Atropisomersmentioning

confidence: 98%

Investigation of the stereodynamics of molecules and catalyzed reactions by CE

Trapp

2010

Electrophoresis

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The investigation of the molecular dynamics of stereoisomers and the study of the kinetics of reactions, in particular of catalyzed reactions, is of fundamental interest in chemistry, biochemistry, and medicine. Understanding how to control the transition state of a reaction allows for a directed design of new catalysts and benign processes. The integration of reactions and capillary or microchip-based electrophoretic separations is highly attractive to perform on-column derivatizations or enzymatic on-column digests of peptides and proteins for further characterization. The present review article focuses on the recent advances to study the stereodynamics of molecules and reaction kinetics of catalyzed processes by means of CE. Models and algorithms to evaluate interconversion profiles obtained by electrophoretic separation techniques are discussed with respect to the challenging demands of high separation efficiencies typical for electrophoretic techniques. Models used for evaluation are based on iterative computer simulation algorithms using the theoretical plate model or stochastic model of chromatography, empirical calculation methods, derived from equations used in chemical engineering, namely Damköhler analysis, and direct access with the approximation function and more recently with the unified equation, which can be applied to all kinds of first-order reactions taking place during a chromatographic or a electrophoretic separation. Furthermore, areas of applications are presented and discussed to give a guideline for using dynamic CE and on-column reaction electrophoresis to study kinetics of reactions and dynamic processes.

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“…19). 44 They obtained pH-dependent energy barriers ranging from 113 to 126 kJ mol 21 that were dramatically reduced by 6-8 kJ mol 21 in the presence of cyclodextrin derivatives. Schurig and coworkers applied the principles of stopped-flow chromatography to gas chromatography albeit with significantly lower accuracy when the measurements required very high temperatures.…”

Section: Chromatographic and Electrophoretic Stopped-flow Analysismentioning

confidence: 99%

Stereolabile chiral compounds: analysis by dynamic chromatography and stopped-flow methods

2005

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Enantiomerization and diastereomerization reactions of chiral compounds play a major role in all aspects of chemistry spanning a wide bridge from drug development to supramolecular chemistry. Traditionally, these reactions are studied by variable-temperature NMR spectroscopy and chiroptical methods such as polarimetry. However, powerful complimentary methods based on chromatography and electrophoresis have been developed and applied to a variety of stereolabile chiral compounds. This tutorial review explains the principles, applications, and limitations of dynamic chromatography and chromatographic and electrophoretic stopped-flow analysis for the investigation of isomerization reactions of chiral compounds.

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Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

Cited by 22 publications

References 42 publications

Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

Investigation of the stereodynamics of molecules and catalyzed reactions by CE

Stereolabile chiral compounds: analysis by dynamic chromatography and stopped-flow methods

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