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Interrogating the configurational stability of atropisomers
Jean-Paul Heeb1, Jonathan Clayden2, Martin D Smith3
1School of Chemistry, University of Bristol, Bristol, UK.
Nature Protocols
|August 4, 2023
Summary
Atropisomers, molecules with stereoisomers from restricted bond rotation, are crucial in various fields. This study details three accessible experimental methods to measure their configurational stability and racemization rates using standard equipment.
Area of Science:
- Organic Chemistry
- Stereochemistry
- Analytical Chemistry
Background:
- Atropisomers are stereoisomers arising from hindered rotation around a single bond.
- These molecules have significant applications in catalysis, medicine, and materials science.
- Configurational stability, or the rate of interconversion between stereoisomers, is a critical property of atropisomers.
Purpose of the Study:
- To present and explain three widely used experimental methods for measuring atropisomer racemization rates.
- To provide detailed experimental procedures for each technique.
- To offer guidance on selecting the appropriate method for new atropisomeric compounds.
Main Methods:
- Kinetic analysis of racemization in enantioenriched samples.
- Dynamic High-Performance Liquid Chromatography (HPLC).
- Variable-temperature Nuclear Magnetic Resonance (NMR) spectroscopy.
Main Results:
- All three methods (kinetic analysis, dynamic HPLC, variable-temperature NMR) are effective for determining racemization rates.
- The described procedures do not require complex experimental setups and utilize standard analytical equipment.
- Racemization rates for new compounds can typically be measured within one day.
Conclusions:
- Accessible experimental techniques are available for characterizing atropisomer configurational stability.
- Standard analytical instruments like NMR and HPLC are sufficient for these measurements.
- Efficient determination of racemization rates is achievable, facilitating research in atropisomer applications.
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