Accelerating stereochemical analysis


A chemosensor has been developed by scientists in the US to speed up the quantitative stereochemical analysis of chiral amino alcohols and diamines. Faster stereochemical analysis will help progress the identification of new asymmetric catalysts.  

Different enantiomers of chiral compounds can have similar physicochemical properties but their biological properties may bear no resemblance to each other. Drugs are often chiral molecules but there can be significant differences between the toxicities of enantiomers.

The administration of just the active enantiomer eliminates the toxic effects of other enantiomers and could make administering lower drug doses possible. Asymmetric catalysts that favour the production of one enantiomer over the other provide a way to produce an excess of desired enantiomers and can lower costs by avoiding the labour-intensive and time-consuming separation of enantiomers.

Driven by industrial demand for efficiency, researchers are producing many potential asymmetric catalysts for drugs and other compounds. Automated laboratory equipment allows catalysts to be tested by running large numbers of catalytic reactions in parallel overnight. However, the discovery process is slowed down by insufficient methods to measure the enantiomeric excess and concentration of products – important values for comparing the efficiency of new catalysts. Current methods to detect enantiomeric excess, such as chiral chromatography, are time-consuming, require tedious purification steps and result in large volumes of waste solvent.

Peng Zhang and Christian Wolf at Georgetown University have made palladium complexes bearing tropos ligands that can act as sensors to stereochemically analyse batches of certain chiral compounds. A chiral recognition process, based on non-covalent interactions between the metal complex and chiral compounds, generates instantaneous and characteristic UV and circular dichroism readouts upon mixing with scalemic substrate samples to quantify their concentration and enantiomeric excess. 

‘Our work shows that sensing with stereodynamic metal complexes holds promise for the development of rapid assays that provide information on both yields and enantiomeric excess of asymmetric reactions,’ says Wolf.

‘The method is very simple and sensitive, and does not require covalent modification of the analyte but works directly,’ says James Canary, an expert in chiral materials at New York University, US. ‘This and other approaches being developed are very interesting and exciting prospects for screening catalysts and reagents for asymmetric synthesis,’ Canary adds.

The team now intend to investigate the use of other metal complexes as sensors for enantiomeric excess.


Related Content

Fundamentals of asymmetric catalysis

28 July 2009 Premium contentReview

news image

The book deals with Lewis acid, Lewis base, metal-based catalysis and organic catalysis

Principles of asymmetric synthesis (2nd edition)

5 July 2013 Review

news image

Chiral choreography

Most Read

Antimicrobial resistance will kill 300 million by 2050 without action

16 December 2014 News and Analysis

news image

UK report says resistance will cost global economy $100 trillion

Cutting edge chemistry in 2014

10 December 2014 Research

news image

We take a look back at the year's most interesting chemical science stories

Most Commented

A bad business

19 December 2014 Critical Point

news image

Targets and assessments can boost productivity at universities – but only if they do not stifle creativity and alienate the...

Unusual 2D silica allotrope predicted

25 June 2014 Research

news image

Simulations say graphene-like silica would become thicker when stretched