High-throughput methods for the development of new catalytic asymmetric reactions

Rapid Enantiomeric Excess Measurements of Enantioisotopomers by Molecular Rotational Resonance Spectroscopy

Recent work in drug discovery has shown that selectively deuterated small molecules can improve the safety and efficacy for active pharmaceutical ingredients. The advantages derive from changes in metabolism resulting from the kinetic isotope effect when deuterium is substituted for a hydrogen atom at a structural position where rate limiting C-H bond breaking occurs. This application has pushed the development of precision deuteration strategies in synthetic chemistry that can install deuterium atoms with high regioselectivity and with stereocontrol. Copper-catalyzed alkene transfer hydrodeuteration chemistry has recently been shown to have high stereoselectivity for deuteration at the metabolically important benzyl C-H position. In this case, stereocontrol results in the creation of enantioisotopomers-molecules that are chiral solely by virtue of the deuterium substitution-and chiral analysis techniques are needed to assess the reaction selectivity. It was recently shown that chiral tag molecular rotational resonance (MRR) spectroscopy provides a routine way to measure the enantiomeric excess and establish the absolute configuration of enantioisotopomers. High-throughput implementations of chiral tag MRR spectroscopy are needed to support optimization of the chemical synthesis. A measurement methodology for high-throughput chiral analysis is demonstrated in this work. The high-throughput ee measurements are performed using cavity-enhanced MRR spectroscopy, which reduces measurement times and sample consumption by more than an order-of-magnitude compared to the previous enantioisotopomer analysis using a broadband MRR spectrometer. It is also shown that transitions for monitoring the enantiomers can be selected from a broadband rotational spectrum without the need for spectroscopic analysis. The general applicability of chiral tag MRR spectroscopy is illustrated by performing chiral analysis on six enantioisotopomer reaction products using a single molecule as the tag for chiral discrimination.

Determination of Enantiomeric Excess and Diastereomeric Excess via Optical Methods. Application to α-methyl-β-hydroxy-carboxylic acids

Characterization of chiral molecules in solution is paramount for measuring reaction success. However, techniques to distinguish between chiral molecules containing more than one stereocenter through the use of optical techniques remains a challenge. Herein, we report a techique using a series of circular dichroism spectra to train multivariate regression models that are capable of predicting the complete speciation of 3-hydroxy-2-methylbutanoic acid stereoisomers. From this, it is possible to rapidly and accurately determine the enantiomeric excess and diastereomeric excess of the solution without the need for chiral chromatography.

Selected Ion Monitoring Using Low-Cost Mass Spectrum Detectors Provides a Rapid, General, and Accurate Method for Enantiomeric Excess Determination in High-Throughput Experimentation

High-Throughput Experimentation (HTE) workflows are efficient means of surveying a broad array of chiral catalysts in the development of catalytic asymmetric reactions. However, use of traditional HPLC-UV/vis methodology to determine enantiomeric excess (ee) from the resulting reactions is often hampered by co-elution of other reaction components, resulting in erroneous ee determination when crude samples are used, and ultimately requiring product isolation prior to ee analysis. In this study, using four published reactions selected as model systems, we demonstrate that the use of LC-MS, SFC-MS, and selected ion monitoring (SIM) mass chromatography provides a highly accurate means to determine ee of products in crude reaction samples using commonplace, low-cost MS detectors. By using ion selection, co-eluting signals can be deconvoluted to provide accurate integrations of the target analytes. We also show that this method is effective for samples lacking UV/vis chromophores, making it ideal for HTE workflows in asymmetric catalysis.

Chiral recognition and enantiomer excess determination based on emission wavelength change of AIEgen rotor

Chiral recognition, such as enantioselective interactions of enzyme with chiral agents, is one of the most important issues in the natural world. But artificial chiral receptors are much less efficient than natural ones. For tackling the chiral recognition and enantiomer excess (ee) analysis, up until now all the fluorescent receptors have been developed based on fluorescence intensity changes. Here we report that the chiral recognition of a large number of chiral carboxylic acids, including chiral agrochemicals 2,4-D, is carried out based on fluorescent colour changes rather than intensity changes of AIEgen rotors. Moreover, the fluorescence wavelength of the AIEgen rotor linearly changes with ee of the carboxylic acid, enabling the ee to be accurately measured with average absolute errors (AAE) of less than 2.8%. Theoretical calculation demonstrates that the wavelength change is ascribed to the rotation of the AIEgen rotor upon interaction with different enantiomers.

Artificial receptors for chiral recognition are important in enantiomer excess analysis but current artificial detectors are based on fluorescence intensity changes only. Here the authors propose a different detection mechanism based on change of the fluorescence emission wavelength of an AIEgen rotor.

Evaluation of droplet-based microfluidic platforms as a convenient tool for lipases and esterases assays

The accurate estimation of kinetic parameters is of fundamental importance for biochemical studies for research and industry. In this paper, we demonstrate the application of a modular microfluidic system for execution of enzyme assays that allow determining the kinetic parameters of the enzymatic reactions such as V_max - the maximum rate of reaction and K_M - the Michaelis constant. For experiments, the fluorogenic carbonate as a probe for a rapid determination of the kinetic parameters of hydrolases, such as lipases and esterases, was used. The microfluidic system together with the method described yields the kinetic constants calculated from the concentration of enzymatic product changes via a Michaelis-Menten model using the Lambert function W(x). This modular microfluidic system was validated on three selected enzymes (hydrolases).

Optical Analysis of Reaction Yield and Enantiomeric Excess: A New Paradigm Ready for Prime Time

This Perspective highlights the advances of optical methods for asymmetric reaction discovery. Optical analysis allows for the determination of absolute configuration, enantiomeric excess and reaction yield that is amenable to high-throughput experimentation. Thus, the synthetic organic community is encouraged to incorporate the methods discussed to expedite the development of high-yielding, enantioselective transformations.

From Substituent Effects to Applications: Enhancing the Optical Response of a Four-Component Assembly for Reporting EE Values

High-throughput screening for asymmetric catalysts has stimulated an interest in optically-based enantiomeric-excess (ee) sensors, primarily for their improved time and cost efficiency when compared to the standard HPLC analysis. We present herein substituent-effect studies on a recently reported Zn(II) multicomponent assembly that is used for chiral, secondary alcohol ee detemination. The systematic altering of assemblies formed from select substituted pyridyl ligands pointed to the conclusion that steric effects dominate the mode of interaction at the pyridyl 3- and 6- positions. From these results we identified a new Zn(II)-centered multicomponent assembly with a higher dynamic range than previously reported. Calibration curves of the CD signals resulting from the new assembly led to an ee assay with a 1.7% error. To further the utility of the new assembly, a correlation was developed between alcohol substituent size to the respective enantiopure CD value.

Supramolecularly fine-regulated enantioselective catalysts

The use of supramolecular interactions in catalysis has undergone major growth in the last decade and has contributed to the major advances achieved in the field of enantioselective catalysis.

Chiral amine enantiomeric excess determination using self-assembled octahedral Fe(II)-imine complexes

A receptor assembly composed of iron(II) triflate and pyridine-2,6-dicarbaldehyde was used to determine the enantiomeric excess (ee) of alpha-chiral primary amines using circular dichroism spectroscopy. The alpha chiral amines condense with the dialdehyde to form a diimine, which forms a 2:1 octahedral complex with iron(II). The ee values of unknown concentrations of alpha-chiral amines were determined by constructing calibration curves for each amine and then measuring the ellipticity at 600 nm. This improves our previously reported assay for ee determination of chiral primary amines by further increasing the wavelength at which CD is measured and reducing the absolute error of the assay.

Well Plate Circular Dichroism Reader for the Rapid Determination of Enantiomeric Excess

Circular dichroism (CD) spectropolarimeters typically employ one photoelastic modulator. However, spectropolarimeters employing two or even four modulators are more versatile and can be used to subvert common measurement errors arising from imperfectly isotropic samples or sample holders. Small linear anisotropies that can cause large errors in CD measurement can be associated with multi-well sample holders. Thus, high-throughput CD analyses in multi-well plates have not yet been demonstrated. One such application is the determination of enantiomeric excess of a library of reaction products. Herein, a spectropolarimeter employing four photoelastic modulators and a translation stage was used to determine the enantiomeric excess of a family of chiral amine complexes much more rapidly than could be achieved with a robotic fluid injection system. These experiments are proof of concept for high-throughput CD analysis. In practice, commercially available glass bottomed well plates are sufficiently strain free such that a simple instrument with just one photoelastic modulator and a vertical optical train should be able to deliver the CD without special considerations given herein. On the other hand, polystyrene well plates cannot be used in this way.

Exploitation of the majority rules effect for the accurate measurement of high enantiomeric excess values using CD spectroscopy

A new method for lowering the error of CD based methods for measuring high enantiomeric excess values is described, which exploits the majority rules effect exhibited by certain helical polymers. A proof of principle experiment was conducted.

High throughput technology: approaches of research in homogeneous and heterogeneous catalysis

High throughput experimentation (HTE) approaches and the choice of the design of experiment (DoE) tools are discussed with regard to their convenience and applicability in homogeneous and heterogeneous catalysis as a concerted workflow. Much attention is given to diverse methodologies and strategies, which are fundamental for the experimental planning. For two target reactions in two case studies presented in this chapter, HTE methods were applied to create and evaluate catalyst libraries. A homogeneous catalyst case study is illustrated first, which deals with parallel synthesis and screening of organometallic catalysts in the polymerisation of ethylene. The second case study (heterogeneous catalysis) focuses on coherent synthesis and testing of dopant effects on the performance of oxidation catalysts in a reaction of transformation of n-butane to maleic anhydride. Supporting examples from the literature described here show that careful planning of libraries and test conditions is vital in high throughput experimentation in order to deliver meaningful results leading to performance improvements or disruptive new findings.

A chiral porous metal-organic framework for highly sensitive and enantioselective fluorescence sensing of amino alcohols

A highly porous and fluorescent metal-organic framework (MOF), 1, was built from a chiral tetracarboxylate bridging ligand derived from 1,1'-bi-2-naphthol (BINOL) and a cadmium carboxylate infinite-chain secondary building unit. The fluorescence of 1 can be effectively quenched by amino alcohols via H-bonding with the binaphthol moieties decorating the MOF, leading to a remarkable chiral sensor for amino alcohols with greatly enhanced sensitivity and enantioselectivity over BINOL-based homogeneous systems. The higher detection sensitivity of 1 is due to a preconcentration effect by which the analytes are absorbed and concentrated inside the MOF channels, whereas the higher enantioselectivity of 1 is believed to result from enhanced chiral discrimination owing to the cavity confinement effect and the conformational rigidity of the BINOL groups in the framework. 1 was quenched by four chiral amino alcohols with unprecedentedly high Stern-Volmer constants of 490-31200 M(-1) and enantioselectivity ratios of 1.17-3.12.

In situ assembly of octahedral Fe(II) complexes for the enantiomeric excess determination of chiral amines using circular dichroism spectroscopy

A method for discriminating between α-chiral primary amine enantiomers is reported. The method utilizes circular dichroism (CD) spectroscopy and a sensing ensemble composed of 2-formyl-3-hydroxypyridine (4) and Fe(II)(TfO)(2). Aldehyde 4 reacts rapidly with chiral amines to form chiral imines, which complex Fe(II) to form a series of diastereomeric octahedral complexes that are CD-active in both the UV and visible regions of the spectrum. NMR studies showed that for enantiomerically pure imine complexes, the Δ-fac isomer is preferred. A statistical analysis of the distribution of stereoisomers accurately modeled the calibration curves for enantiomeric excess (ee). CD signals appearing in the UV region were bisignate, and the nulls of the CD signals were coincident with maxima in the UV spectrum, consistent with exciton coupling. Time-dependent density functional theory and semiempirical calculations confirmed that the CD signals in the UV region arise from coupling of the π-π* transitions in the imine chromophores and that they can be used to describe the signs and magnitudes of the curves accurately. The CD signals in the visible region arise from metal-to-ligand charge-transfer bands, and these signals can be used to determine the ee values of chiral amines with an average absolute error of ±5%. Overall, the strategy presented herein represents a facile in situ assembly process that uses commercially available simple reagents to create large optical signals indicative of ee values.

Rapid determination of enantiomeric excess of α-chiral cyclohexanones using circular dichroism spectroscopy

Ketone handedness was discriminated using circular dichroism (CD) spectroscopy by monitoring the metal-to-ligand charge transfer (MLCT) bands of complexes between [Cu(I)((S)-1)(CH(3)CN)(2)]PF(6) and derivatized α-chiral cyclohexanones (4). This method was able to quantify the enantiomeric excess of unknown samples using a calibration curve, giving an absolute error of ±7%. The analysis was fast, allowing potential application of this assay in high-throughput screening (HTS).

Hybrid bidentate phosphorus ligands in asymmetric catalysis: privileged ligand approach vs. combinatorial strategies

In this perspective the development of chiral phosphorus ligands for asymmetric catalysis is discussed, with a special focus on hybrid bidentate phosphorus ligands, in particular phosphine-phosphoramidites. An attempt is made to compare privileged ligand and combinatorial approaches to ligand development--for which the class of phosphine-phosphoramidite ligands is well suited--highlighting differences, similarities and their complementary use.

Electrochemical method for the determination of enantiomeric excess of binol using redox-active boronic acids as chiral sensors

A chiral ferrocene-based boronic acid interacts with (R)- and (S)-Binol to form two complexes that exhibit significantly different ferrocene-based electrode potentials. This difference in redox behavior can be exploited to demonstrate in principle how high levels of enantiomeric excess in a mixture of enantiomers can be quantified and read-out using an electrochemical method.

The uses of supramolecular chemistry in synthetic methodology development: examples of anion and neutral molecular recognition

The principles of supramolecular chemistry have successfully permeated through a broad range of organic chemistry subdisciplines. One subdiscipline that is not routinely associated with supramolecular chemistry is that of organic synthetic methodology. Though sometimes indiscernible, non-bonded and bonding supramolecular interactions play a large role in chemical reactions and catalysis. Many synthetic methods hinge on the creation of anionic charge, albeit just partial, at some step during this process, and hence are prime targets for molecular recognition interactions. Examples are artificial enzymes, biomimetic catalysis, organocatalysis, and many of the catalysts that are derived from a combinatorial screen. Further, supramolecular chemistry is playing an increasingly large role in high-throughput analytical techniques. This tutorial review ties together supramolecular approaches to methodology creation, combinatorial screening, and analytical protocols. The goal is to show, and further predict, that supramolecular chemistry will continually increase its impact in organic synthetic methodology development.

Catalyst selection based on intermediate stability measured by mass spectrometry

The power of natural selection through survival of the fittest is nature's ultimate tool for the improvement and advancement of species. To apply this concept in catalyst development is attractive and may lead to more rapid discoveries of new catalysts for the synthesis of relevant targets, such as pharmaceuticals. Recent advances in ligand synthesis using combinatorial methods have allowed the generation of a great diversity of catalysts. However, selection methods are few in number. We introduce a new selection method that focuses on the stability of catalytic intermediates measured by mass spectrometry. The stability of the intermediate relates inversely to the reactivity of the catalyst, which forms the basis of a catalyst-screening protocol in which less-abundant species represent the most-active catalysts, 'the survival of the weakest'. We demonstrate this concept in the palladium-catalysed allylic alkylation reaction using diphosphine and IndolPhos ligands and support our results with high-level density functional theory calculations.

A facile circular dichroism protocol for rapid determination of enantiomeric excess and concentration of chiral primary amines

A protocol for the rapid determination of the absolute configuration and enantiomeric excess (ee) of alpha-chiral primary amines with potential applications in asymmetric reaction discovery has been developed. The protocol requires derivatization of alpha-chiral primary amines through condensation with pyridine carboxaldehyde to quantitatively yield the corresponding imine. The Cu(I) complex with 2,2'-bis (diphenylphosphino)-1,1'-dinaphthyl (BINAP--Cu(I)) with the imine yields a metal-to-ligand charge-transfer (MLCT) band in the visible region of the circular dichroism (CD) spectrum upon binding. Diastereomeric host-guest complexes give CD signals of the same signs but different amplitudes, allowing for differentiation of enantiomers. Processing the primary optical data from the CD spectrum with linear discriminant analysis (LDA) allows for the determination of the absolute configuration and identification of the amines, and processing with a supervised multilayer perceptron artificial neural network (MLP-ANN) allows for the simultaneous determination of the ee and concentration. The primary optical data necessary to determine the ee of unknown samples is obtained in two minutes per sample. To demonstrate the utility of the protocol in asymmetric reaction discovery, the ee values and concentrations for an asymmetric metal-catalyzed reaction are determined. The potential of the application of this protocol in high-throughput screening (HTS) of ee is discussed.

High-Throughput Screening of the Asymmetric Decarboxylative Alkylation Reaction of Enolate-Stabilized Enol Carbonates

The use of high-throughput screening allowed for the optimization of reaction conditions for the palladium-catalyzed asymmetric decarboxylative alkylation reaction of enolate-stabilized enol carbonates. Changing to a non-polar reaction solvent and to an electron-deficient PHOX derivative as ligand from our standard reaction conditions improved the enantioselectivity for the alkylation of a ketal-protected,1,3-diketone-derived enol carbonate from 28% ee to 84% ee. Similar improvements in enantioselectivity were seen for a β-keto-ester derived- and an α-phenyl cyclohexanone-derived enol carbonate.

Molecular recognition and self-assembly special feature: A general protocol for creating high-throughput screening assays for reaction yield and enantiomeric excess applied to hydrobenzoin

A general approach to high-throughput screening of enantiomeric excess (ee) and concentration was developed by using indicator displacement assays (IDAs), and the protocol was then applied to the vicinal diol hydrobenzoin. The method involves the sequential utilization of what we define herein as screening, training, and analysis plates. Several enantioselective boronic acid-based receptors were screened by using 96-well plates, both for their ability to discriminate the enantiomers of hydrobenzoin and to find their optimal pairing with indicators resulting in the largest optical responses. The best receptor/indicator combination was then used to train an artificial neural network to determine concentration and ee. To prove the practicality of the developed protocol, analysis plates were created containing true unknown samples of hydrobenzoin generated by established Sharpless asymmetric dihydroxylation reactions, and the best ligand was correctly identified.

Using enantioselective indicator displacement assays to determine the enantiomeric excess of alpha-amino acids

Enantioselective indicator displacement assays (eIDAs) were used for the determination of enantiomeric excess (ee) of alpha-amino acids as an alternative to the labor-intensive technique of chromatography. In this study, eIDAs were implemented by the use of two chiral receptors [(Cu(II)(1)](2+), [Cu(II)(2)](2+)) in conjunction with the indicator chrome azurol S. The two receptors were able to enantioselectively discriminate 13 of the 17 analyzed alpha-amino acids. Enantiomeric excess calibration curves were made using both receptors and then used to analyze true test samples to check the system's ability to determine ee accurately. The proposed method uses a conventional UV-vis spectrophotometer to monitor the colorimetric signal, which allows for a potential high-throughput screening (HTS) method for determining ee. The techniques created consistently produced results accurate enough for rapid preliminary determination of ee.

Transitioning enantioselective indicator displacement assays for alpha-amino acids to protocols amenable to high-throughput screening

Enantioselective indicator displacement assays (eIDAs) for alpha-amino acids were conducted in a 96-well plate format to demonstrate the viability of the technique for the high-throughput screening (HTS) of enantiomeric excess (ee) values. Chiral receptors [Cu(II)(1)](2+) and [Cu(II)(2)](2+) with the indicator chrome azurol S were implemented for the eIDAs. Enantiomeric excess calibration curves were made using both receptors and then used to analyze true test samples. These results were compared to those previously obtained with a conventional UV-vis spectrophotometer, and they showed little to no loss of accuracy, while the speed of analysis was increased. A sample of valine of unknown ee was synthesized through an asymmetric reaction to produce a realistic reaction sample, which was analyzed using receptor [Cu(II)(1)](2+). The experimentally determined ee using our eIDA was compared to that obtained by chiral HPLC and (1)H NMR chiral shift reagent analysis. This gave errors of 4.7% and 12.0%, respectively. In addition to the use of ee calibration curves, an artificial neural network (ANN) was used to determine the % L-amino acid of the test samples and of the sample of valine of unknown ee from the asymmetric reaction. This method obtained errors of 5.9% and 2.2% compared to chiral HPLC and (1)H NMR chiral shift reagent analysis, respectively. The technique using calibration curves for the determination of ee on a 96-well plate allows one to determine 96 ee values in under a minute, enabling its use for HTS of asymmetric reactions with acceptable accuracy.

"Cassette" in situ enzymatic screening identifies complementary chiral scaffolds for hydrolytic kinetic resolution across a range of epoxides

‘Cassette’-ISES (In Situ Enzymatic Screening) Identifies Complementary Chiral Scaffolds for Hydrolytic Kinetic Resolution Across a Range of Epoxides

A new ‘Cassette’-In Situ Enzymatic Screen (ISES) for combinatorial catalysis is introduced. This allows the experimentalist to obtain an information-rich readout, in real time, providing an estimate of the sense and magnitude of enantioselectivity across more than one substrate. In its first iteration, the screen identified CoIII-salen catalysts with β-pinene- and α-naphthylalanine-derived chiral scaffolds with broad, yet complementary, substrate specificities.

Efficient Solid-Phase Synthesis of Peptide-Based Phosphine Ligands: Towards Combinatorial Libraries of Selective Transition Metal Catalysts

A new methodology for the solid-phase synthesis of peptide-based phosphine ligands has been developed. Solid supported peptide scaffolds possessing either primary or secondary amines were synthesised using commercially available Fmoc-protected amino acids and readily available Fmoc-protected amino aldehydes for reductive alkylation, in standard solid-phase peptide synthesis (SPPS). Phosphine moieties were introduced by phosphinomethylation of the free amines as the final solid-phase synthetic step, immediately prior to complexation with palladium(II), thus avoiding tedious protection/deprotection of the phosphine moieties during the synthesis of the ligands. The extensive use of commercial building blocks and standard SPPS makes this methodology well suited for the generation of solid-phase combinatorial libraries of novel ligands. Furthermore, it is possible to generate several different phosphine ligand libraries for every peptide scaffold library synthesised, by functionalising the scaffold libraries with different phosphine moieties. The synthesised ligands were characterised on solid support by conventional (31)P NMR spectroscopy and, cleaved from the support, as their phosphine oxides by HPLC, (1)H NMR, (31)P NMR and high resolution ESMS. Palladium(II) allyl complexes were generated from the resin bound ligands and to demonstrate their catalytic properties, palladium catalysed asymmetric allylic substitution reactions were performed. Good yields and moderate enantioselectivity was obtained for the selected combination of catalysts and substrate, but most importantly the concept of this new methodology was proven. Screening of ligand libraries should afford more selective catalysts.

In situ formation of ligand and catalyst—application in ruthenium-catalyzed enantioselective reduction of ketones

The direct in situ formation of highly efficient ruthenium-catalysts for the asymmetric reduction of ketones was obtained by combining chiral ligand building blocks with a ruthenium precursor.

In situ enzymatic screening (ISES) of P,N-ligands for Ni(0)-mediated asymmetric intramolecular allylic amination

An in situ enzymatic screening (ISES) approach to rapid catalyst evaluation recently pointed to Ni(0) as a new candidate transition metal for intramolecular allylic amination. This led to further exploration of chiral bidentate phosphine ligands for such transformations. Herein, a variety of P,N-ligands are examined for this Ni(0)-chemistry, using a model reaction leading into the vinylglycinol scaffold. On the one hand, an N,N-bis(2-diphenylphosphinoethyl)alkylamine ('PNP') ligand proved to be the fastest ligand yet seen for this Ni(0)-transformation. On the other, phosphinooxazoline (PHOX) ligands of the Pfaltz-Helmchen-Williams variety gave the highest enantioselectivities (up to 51% ee) among P,N-ligands examined.

Simultaneous determination of phenylglycidol enantiomers and cinnamyl alcohol in asymmetric epoxidation processes by chiral liquid chromatography

A high-performance liquid chromatographic method has been developed for the simultaneous determination of phenylglycidol enantiomers and cinnamyl alcohol (CA). Separations were achieved on an amylose tris(3, 5-dymethylphenylcarbamate) chiral stationary phase (Chiralpak AD). The effect of concentration of organic modifier (2-propanol and ethanol) in the mobile phase and flow-rate was studied. The mobile phase selected consisted of a mixture of n-hexane-ethanol (85:15, v/v) with a flow-rate of 1.2 ml/min. The UV-vis detector was set at 254 nm. Resolution for the phenylglycidol enantiomers in the suitable chromatographic conditions was 2.4 with an analysis time of 12 min. The method developed was validated and was found to be linear in the range from 5 x 10(-4) to 3 x 10(-2) M, for phenylglycidol enantiomers and in the range from 5 x 10(-5) to 1 x 10(-3) M, for CA (r > 0.999 for the three compounds). Repeatability and intermediate precision for the three analytes at three different concentrations were below 3.6 and 2.8% R.S.D., respectively. This method has been applied to study the asymmetric epoxidation of CA with titanium(IV) alkoxide compounds as catalysts in order to evaluate their catalytic activity and stereoselectivity of the epoxidation processes.