Rapid determination of enantiomeric excess: a focus on optical approaches

Abstract

High-throughput screening (HTS) methods are becoming increasingly essential in discovering chiral catalysts or auxiliaries for asymmetric transformations due to the advent of parallel synthesis and combinatorial chemistry. Both parallel synthesis and combinatorial chemistry can lead to the exploration of a range of structural candidates and reaction conditions as a means to obtain the highest enantiomeric excess (ee) of a desired transformation. One current bottleneck in these approaches to asymmetric reactions is the determination of ee, which has led researchers to explore a wide range of HTS techniques. To be truly high-throughput, it has been proposed that a technique that can analyse a thousand or more samples per day is needed. Many of the current approaches to this goal are based on optical methods because they allow for a rapid determination of ee due to quick data collection and their parallel analysis capabilities. In this critical review these techniques are reviewed with a discussion of their respective advantages and drawbacks, and with a contrast to chromatographic methods (180 references).

Surface Stiffness—a Parameter for Sensing the Chirality of Saccharides

“…39 In general, ee values are measured using chiral chromatographic techniques, which have some shortcomings, such as time consumption and high costs (i.e., high purity solvents and chiral column replacement). More importantly, until now, some special enantiomers could not be separated using chiral columns.…”

Nanophotonics and supramolecular chemistry

“…Photonic aspects of supramolecular systems can be applied for use in materials detection [17,[35][36][37][38][39]. Detection of particular chemical species accompanied by specific variations of fluorescence emission is a powerful method in analytical chemistry.…”

Chiral Recognition by Fluorescence: One Measurement for Two Parameters

“…To date, a number of techniques are under development for the high-throughput enantiomeric composition determination [13][14][15][16][17], including time resolved IR-thermographic method [18][19][20][21], electron spray mass spectrometry [22][23][24][25][26], capillary electrophoresis [27], UV/Vis [28][29][30], circular dichroism [31,32], and fluorescence [33,34]. Among these approaches, optical methods have been attracting increasing attention due to their ability for quick data collection and compatibility with high-throughput screening system.…”

“…Among these approaches, optical methods have been attracting increasing attention due to their ability for quick data collection and compatibility with high-throughput screening system. Anslyn has recently reviewed the optical approaches for the rapid enantiomeric composition determination [17]. For an asymmetrical catalytic reaction, both the yield and enantiomeric purity of the product are the essential two parameters needed to evaluate the efficiency of a chiral catalyst.…”