Planar chiral molecular structures

Schlögl, K.

doi:10.1007/3-540-13569-3_2

Cited by 62 publications

(15 citation statements)

References 153 publications

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“…9, 10 The replacement of methylene units by heteroatoms affects the absolute length of the bridge and the magnitude of the rotational barrier due to different C-heteroatom bond lengths in relation to the average C-C bond length (1.54 Å). 11 For example, the shorter C-O distances (1.43 Å) in 1,11-dioxa [11]paracyclophanes increase the energy barriers by 8-10 kJ/mol compared to the carbocyclic analogs.…”

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confidence: 99%

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

et al. 2001

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A number of variously monosubstituted 1,n-diaza[n]paracyclophanes (n = 10-12), which show planar chirality and atropisomerism due to hindered rotation about single bonds, were synthesized via a classical route to analyze their stereodynamic properties. Racemic analytes with 10- and 11-membered bridges were resolved by capillary zone electrophoresis (CZE) in acidic phosphate buffers (pH 2.5-4.5) employing permethylated beta- and gamma-cyclodextrin as chiral additives. Moreover, cyclodextrin mediated CZE was used in a discontinuously driven mode for investigations of the rotational interconversion process of conformationally labile homologues (n = 11). In stopped-flow experiments, after baseline separation enantiomers were partially enantiomerized in situ inside the capillary by heating. The rate constants (k(enan) = 1/2 k(rac)) and rotational energy barriers (Delta G(++)) were determined from the resulting enantiomeric ratios. Energy barriers between 113-126 kJ/mol were found depending on the substituent of the benzene ring and the degree of ionization of the amino groups in bridgehead positions. The energy barriers increased in order of the substituents: NO(2) >> CF(3) > Br > Cl > CH(3) approximately F. In addition, the rotational energy barriers were decreased by approximately 6-8 kJ/mol in the presence of the chiral selector.

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confidence: 99%

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

et al. 2001

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“…1 H NMR spectra of 1 were recorded in DMSO-d 6 in the temperature range 20 to 80°C and well-resolved spectra were obtained up to 40°C. Parts of the 1 H NMR spectra containing signals from hydroxymethyl group are shown in Fig.…”

Section: Variable Temperature (Vt) Nmr Studymentioning

confidence: 99%

“…Non-planarity of the central ring, and, in particular, its conformational stability, may significantly affect the compounds' biological properties. These compounds have a chirality plane, and inversion of the non-planar ring through this plane leads to conformational or planar chiral enantiomers (planar chirality is stereoisomerism resulting from the arrangement of out-of-plane groups relative to the chirality plane [4][5][6]). According to some authors, these conformers can also be regarded as atropisomers, i.e.…”

Section: Introductionmentioning

confidence: 99%

Conformational properties and chiral separation of dibenzo[b,f]thieno[3,4-d]-fused oxepines and thiepines

Landek

Pešić

et al. 2013

Monatsh Chem

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The dynamic properties of planar chiral 1-hydroxymethyl-substituted dibenzo[b,f]thieno[3,4-d]-fused oxepine and thiepine derivatives have been investigated by use of variable-temperature nuclear magnetic resonance spectroscopy combined with line-shape analysis, chiral column chromatography, and molecular modelling. NMR data and computational studies revealed the height of the energy barrier for ring inversion in thiepine derivatives was sufficient to enable the existence of a pair of conformational enantiomers at ambient temperature. Their resolution was achieved by chiral column high-performance liquid chromatography (HPLC). The absolute conformation of the enantiomers is proposed. This is the first chromatographic separation of planar chiral enantiomers of [b,d,f]-fused thiepine derivatives.

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“…Medium rings containing an embedded (E)-alkene are known to take up left-or right-handed helical topologies whose absolute configurations are defined by a planar chirality. 1,2 Individual factors influencing the configuration of the macrocycle include size, 3,4 points of articulation, 5,6 and substituents that adorn the ring. 7 Interplay between these features governs the energetics of transannular interactions and ultimately the low energy conformation of a given structure.…”

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Remote induction of asymmetry in [13]-macro-dilactone topology by a single stereogenic center

Fyvie

Peczuh

2008

Chem. Commun.

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Planar chiral molecular structures

Cited by 62 publications

References 153 publications

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

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

Conformational properties and chiral separation of dibenzo[b,f]thieno[3,4-d]-fused oxepines and thiepines

Remote induction of asymmetry in [13]-macro-dilactone topology by a single stereogenic center

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