The absolute configuration of simple aliphatic alcohols through a chemical/computational approach: triarylether derivatives of (+)-endo-2-norborneol as a case study

Amplification of the chiroptical response of UV-transparent amines and alcohols by N-phthalimide derivatization enabling absolute configuration determination through ECD computational analysis

The stereoselective transformation of chiral UV-transparent amines and alcohols to phthalimides has proved to be a simple and efficient method to enhance the chiroptical response of these substrates allowing their reliable absolute configuration determination by computational analysis of ECD spectra. Such a transformation also leads to a significant reduction in the molecular conformational flexibility thus simplifying the conformational analysis required by the computational treatment. The method described herein thus allows the absolute configuration assignment to these challenging substrates to be much easier and reliable.

Chirality sensing using stereodynamic probes with distinct electronic circular dichroism output

Circular dichroism (CD) spectroscopy is one of the most useful techniques for the stereochemical analysis of chiral biopolymers and fine chemicals. It has become invaluable for the assignment of the absolute configuration, the study of conformational isomers, and the determination of racemization kinetics of CD active chiral compounds. Molecular interactions between a nonracemic chiral substrate and a chromophoric, CD-silent probe that is achiral or exists as a racemic mixture of rapidly interconverting enantiomeric conformations or configurations can induce a strong, characteristic chiroptical readout. A covalent or noncovalent binding event that coincides with a well-defined asymmetric induction process can effectively imprint the chiral information of the substrate on the stereodynamic sensor and thus generate intense Cotton effects in the UV region of the latter. The probe can thus function as a stereochemical reporter unit and analysis of the CD spectrum often provides accurate information about the absolute configuration and enantiomeric composition of the substrate used. In this review, recent developments in circular dichroism analysis of chiral compounds with stereodynamic probes are described and particular emphasis is given to sensor design, chiral induction processes and applications scope.