Introduction

The methods of generating enantiomers are classified roughly into asymmetric synthesis, crystallization, enzyme reaction, and optical resolution by chromatography. In particular, normal phase chromatography with chiral stationary phases has been used in various fields such as pharmaceuticals, agrochemicals, natural products, biomolecules, and functional materials because of the cost efficiency. Recently, preparative SFC, which provides faster, higher- separation analysis and easier post handling of fractions than HPLC, has become a main stream as an efficient method of producing enantiomers in the drug discovery stage.

Nuclear magnetic resonance (NMR), X-ray diffraction (XRD), electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and tandem mass spectrometry (MS/MS) are used for qualitative analysis and structural analysis of enantiomers of chiral substances. In general, these analyses require the sample amount from 1 to 100 mg. Circular dichroism (CD) spectroscopy is a useful technique because it doesn’t require a lot of sample amount and is easy to operate compared to other methods. It is possible to determine the absolute configuration of chiral molecules by comparing the calculated theoretical spectrum and experimental one.

In this presentation, we separated and fractionated enantiomers of chiral substances using semi-preparative SFC and applied the obtained enantiomer samples to spectra measurements by ECD and VCD spectrometers. Furthermore, we determined the absolute configuration of each enantiomer by calculating theoretical ECD and VCD spectra.

Keywords

electronic circular dichroism (ECD), vibrational circular dichroism (VCD), chiral separation, SFC, HPLC, enantiomer