Electrospray ionization mass and tandem mass spectra of a series of N‐pyrazolylmethyl and N‐triazolylmethyl N‐phenylpiperazines: new dopaminergic ligands with potential antipsychotic properties

Abstract

Recently, two analogous series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines have been prepared and found to be potential antipsychotic drugs acting as new selective ligands of the dopamine D2 receptor. Herein we report a systematic study of their high-resolution electrospray ionization mass and tandem mass spectra in which the main dissociation routes of their protonated molecules are determined and rationalized. The ESI-MS/MS data is very characteristic for both series allowing straightforward isomeric differentiation. A single and dominant fragment ion for the pyrazole series and four major fragment ions for the triazole series are useful for selective reaction MS monitoring of these potential drugs in biological fluids.

Purification and Quantification of an Isomeric Compound in a Mixture by Collisional Excitation in Multistage Mass Spectrometry Experiments

“…However, since the loss of N 2 is also present in MS/MS spectra of PLA Cyc , traces of linear isomer in cyclic PLA samples cannot be detected by visual inspection of MS/MS spectra only, regardless of the excitation voltage used. It must be noted that the observation of N 2 loss from both the azide and triazole groups (as we reported already , ) actually contradicts previous reports assigning N 2 loss as a diagnostic fragment of triazole only (that may be structure-dependent) and as a clear evidence for the click-chemistry process to occur. − The structure of this important m / z 1508.6 fragment ion has been studied by MS 3 experiments (Figure S-2). PLA Cyc shows two additional peaks as compared with PLA Lin , leading us to the conclusion that, again, traces of linear isomers in cyclic PLA samples cannot be detected by simple visual inspection of the MS 3 spectra.…”

The Mechanism of Tröger's Base Formation Probed by Electrospray Ionization Mass Spectrometry

“…Furthermore, in regard to the ESI-MS/MS characterization of the intercepted species, intermediate [ 4a − H] + of m / z 237 (Figure S1c) contravenes the even-electron rule 26 to lose a CH 3 radical, thus forming the fragment ion of m / z 222. Scheme rationalizes this loss, which forms a relatively stable distonic radical cation, , but the main dissociation pathway for [ 4a − H] + is by retro-addition to form the species [ 2 + H] + of m / z 120 (Figure S1c).

5 ESI-MS screening for the reaction solution formed by mixing TFA solutions of p -toluidine ( 1 ) with urotropine ( 15 ) on-line using a microreactor coupled just before the ESI source and reaction time of ca.

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Determination of Benzotriazole Corrosion Inhibitors from Aqueous Environmental Samples by Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry

“…The loss of molecular nitrogen to form an azirine cation is the initial fragmentation of all molecular cations that are likely ionized at the triazole ring system (Figure ). This fragmentation corresponds to N-substituted 1,2,3-triazoles . Then hydrocyanic acid is expelled to form a cyclopentadienyl cation.…”