Atropisomerism of 2,2′‐Diaryl‐1,1′‐binaphthalenes Containing Three Stereo­genic Axes: Experimental and Computational Study

Ehn, Marcel; Vassilev, Nikolay G.; Pašteka, Lukáš F.; Dangalov, Miroslav; Putala, Martin

doi:10.1002/ejoc.201500840

Cited by 8 publications

(4 citation statements)

References 48 publications

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“…The rotational dynamics of 2,2‐binaphthyl chiral auxiliaries is related to their enantioselectivity . The rotational barriers in 2,2‐diaryl‐1,1‐binaphthalenes 41 have been determined by 1 H‐ 1 H EXSY . They were consistent with those determined at higher temperatures by lineshape analysis.…”

Section: Intramolecular Rotationsupporting

confidence: 72%

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Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Nikitin

O'Gara

2019

Chemistry A European J

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Detailed mechanistic information is crucial to our understanding of reaction pathways and selectivity. Dynamic exchange NMR techniques, in particular 2D exchange spectroscopy (EXSY) and its modifications, provide indispensable intricate information on the mechanisms of organic and inorganic reactions and other phenomena, for example, the dynamics of interfacial processes. In this Review, key results from exchange NMR studies of small molecules over the last few decades are systemised and discussed. After a brief introduction to the theory, the key types of dynamic processes are identified and fundamental examples given of intra‐ and intermolecular reactions, which, in turn, could involve, or not, bond‐making and bond‐breaking events. Following that logic, internal molecular rotation, intramolecular stereomutation and molecular recognition will first be considered because they do not typically involve bond breaking. Then, rearrangements, substitution‐type reactions, cyclisations, additions and other processes affecting chemical bonds will be discussed. Finally, interfacial molecular dynamics and unexpected combinations of different types of fluxional processes will also be highlighted. How exchange NMR spectroscopy helps to identify conformational changes, coordination and molecular recognition processes as well as quantify reaction energy barriers and extract detailed mechanistic information by using reaction rate theory in conjunction with computational techniques will be shown.

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Section: Intramolecular Rotationsupporting

confidence: 72%

“…[68] The rotational barriers in 2,2-diaryl-1,1-binaphthalenes 41 have been determined by 1 H-1 HE XSY. [69] They were consistentw ith those determined at higher temperatures by lineshape analysis.…”

Section: Coupled Rotors:propellersmentioning

confidence: 99%

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Nikitin

O'Gara

2019

Chemistry A European J

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“…The comparison of experimental and DFT calculated barriers can reveal the exchange mechanism. This protocol, including the combination of dynamic NMR and DFT calculation, was recently successfully applied for studying the structure and exchange mechanism of palladium complexes [ 65 , 66 , 69 ], ortho-diphenylphosphinobenzenecarboxamide ligands [ 67 ], galantamine derivatives [ 68 ], and atropisomers of 2,20-diaryl-1,10-binaphthalenes containing three stereogenic axes [ 80 ].…”

Section: Resultsmentioning

confidence: 99%

Structure and Conformational Mobility of OLED-Relevant 1,3,5-Triazine Derivatives

et al. 2023

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A series of OLED-relevant compounds, consisting of 1,3,5-triazine core linked to various aromatic arms by amino group, has been synthesized and characterized. The studied compounds exist in solution as a mixture of two conformers, a symmetric propeller and asymmetric conformer, in which one of the aromatic arms is rotated around the C-N bond. At temperatures below −40 °C, the VT NMR spectra in DMF-d7 are in a slow exchange regime, and the signals of two conformers can be elucidated. At temperatures above 100 °C, the VT NMR spectra in DMSO-d6 are in a fast exchange regime, and the averaged spectra can be measured. The ratio of symmetric and asymmetric conformers in DMF-d7 varies from 14:86 to 50:50 depending on the substituents. The rotational barriers of symmetric and asymmetric conformers in DMF-d7 were measured for all compounds and are in the interval from 11.7 to 14.7 kcal/mol. The ground-state energy landscapes of the studied compounds, obtained by DFT calculations, show good agreement with the experimental rotational barriers. The DFT calculations reveal that the observed chemical exchange occurs by the rotation around the C(1,3,5-triazine)-N bond. Although some of the compounds are potentially tautomeric, the measured absorption and emission spectra do not indicate proton transfer neither in the ground nor in the excited state.

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“…Quantitative two-dimensional exchange NMR spectroscopy ( 1 H- 1 H EXSY) experiments in d 2 -TCE at 25 °C revealed rate constants − for the bowl inversion and directionality reversal of 1d of 3.05 ± 0.10 and 0.27 ± 0.05 s –1 , respectively, corresponding to energy barriers (Δ G ‡ 25°C ) of 70.2 kJ mol –1 for bowl inversion and 76.2 kJ mol –1 for directionality reversal (Figure ). The bowl inversion of 1d is thus an order of magnitude faster than its directionality reversal in d 2 -TCE, which is also the case in d 6 -benzene, where similar energy barriers were obtained (Table S23).…”

Section: Resultsmentioning

confidence: 99%

Dynamic and Persistent Cyclochirality in Hydrogen-Bonded Derivatives of Medium-Ring Triamines

Morris,

Wales,

Echavarren

et al. 2023

J. Am. Chem. Soc.

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Cyclic triureas derived from 1,4,7-triazacyclononane (TACN) were synthesized; X-ray crystallography showed a chiral bowl-like conformation with each urea hydrogen-bonded to its neighbor with uniform directionality, forming a "cyclochiral" closed loop of hydrogen bonds. Variable-temperature 1 H NMR, 1 H-1 H exchange spectroscopy, Eyring analysis, computational modeling, and studies in various solvents revealed that cyclochirality is dynamic (ΔG ‡ 25°C = 63−71 kJ mol −1 in noncoordinating solvents), exchanging between enantiomers by two mechanisms: bowl inversion and directionality reversal, with the former subject to a slightly smaller enantiomerization barrier. The enantiomerization rate substantially increased in the presence of hydrogen-bonding solvents. Population of only one of the two cyclochiral hydrogen-bond directionalities could be induced by annulating one ethylene bridge with a trans-cyclohexane. Alternatively, enantiomerization could be inhibited by annulating one ethylene bridge with a cis-cyclohexane (preventing bowl inversion) and replacing one urea function with a formamide (preventing directionality reversal). Combining these structural modifications resulted in an enantiomerization barrier of ΔG ‡ 25°C = 93 kJ mol −1 , furnishing a planar-chiral, atropisomeric bowlshaped structure whose stereochemical stability arises solely from its hydrogen-bonding network.

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Atropisomerism of 2,2′‐Diaryl‐1,1′‐binaphthalenes Containing Three Stereogenic Axes: Experimental and Computational Study

Cited by 8 publications

References 48 publications

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Structure and Conformational Mobility of OLED-Relevant 1,3,5-Triazine Derivatives

Dynamic and Persistent Cyclochirality in Hydrogen-Bonded Derivatives of Medium-Ring Triamines

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Atropisomerism of 2,2′‐Diaryl‐1,1′‐binaphthalenes Containing Three Stereo­genic Axes: Experimental and Computational Study

Cited by 8 publications

References 48 publications

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy

Structure and Conformational Mobility of OLED-Relevant 1,3,5-Triazine Derivatives

Dynamic and Persistent Cyclochirality in Hydrogen-Bonded Derivatives of Medium-Ring Triamines

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Atropisomerism of 2,2′‐Diaryl‐1,1′‐binaphthalenes Containing Three Stereogenic Axes: Experimental and Computational Study