An ESI-MS Method to Determine Yield and Enantioselectivity in a Single Assay

Abstract

Abstract. A mass spectrometry assay is presented here that allows for the simultaneous determination of yield and enantioselectivity in a single analysis. The assay makes use of molecules that are structurally similar to the analytes of interest as standards. The assay predicts the yields of the reactions reasonably well and with little error. For example, in the pig liver esterase catalyzed hydrolysis of one prochiral malonate, the yield predicted by the assay was 72%, while larger scale isolated reaction yields were within 5% of this value. This assay provides a fast method to determine yield and enantioselectivity in one analysis. The strengths and limitations of this method are discussed.

Quantitative Determination of Active Species Transforming the R-NHC Coupling Process under Catalytic Conditions

“…Quantitative MS often employs deuterated internal standards, − leveraging the MS signal intensities of the substrate and standard for quantitation. Ideal internal standards should share similar ionization response factors with the subject substrate and not have overlapping isotopic distributions. , Interestingly, while electrospray ionization mass spectrometry (ESI-MS) has been applied for the qualitative observation of compound formation in real catalytic systems, ,, quantitative analysis has been reported only for model conditions at 5 mol % Pd/NHC loading . Its quantitative application with deuterated standards for the assessment of NHC ligand transformation products has largely not been explored.…”