Online Inductive Electrospray Ionization Mass Spectrometry as a Process Analytical Technology Tool To Monitor the Synthetic Route to Anagliptin

Inductive electrospray ionization (iESI) is an ambient ionization method that is particularly well-suited to online reaction monitoring. It allows the potential of electrospray mass spectrometry (MS) to be realized as a routine process analytical technology (PAT) tool to monitor practical synthetic reactions in real time. In this study, a synthetic route to Anagliptin (target API) was successfully monitored using online iESI-MS. Starting materials not seen by traditional reaction monitoring tools (HPLC-UV/Vis and GC-FID) were observed, as well as water-sensitive reagents and intermediates which cannot easily be followed by other methods. Online tandem mass spectrometry (MS/MS) was used to characterize chemical species in the reaction mixture. Impurities and byproducts were identified, and information on the progress of byproduct formation enabled implementation of strategies to eliminate these byproducts in the course of the reaction. This work demonstrates how iESI-MS can be employed to obtain comprehensive information and solutions to some practical problems that occur in small-molecule synthetic reaction monitoring.