Mass spectrometry of pyrimidine derivatives: Electron impact‐induced decomposition of molecular ions of 4‐amino‐substituted and 4‐amino‐disubstituted 1,2‐dihydro‐1‐methylpyrimidin‐2‐ones

Plaziak, Adam S.; Celewicz, Lech; Ciszewski, Krzystof; Golankiewicz, K.

doi:10.1002/oms.1210261008

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…Electron impact (EI) mass spectra of 4-amino-substituted and 4-amino-disubstituted 1,2dihydro-1-methylpyrimidin-2-ones ( Fig. 20) were reported [57]. The EI-induced decomposition of their molecular ions is significantly dependent on the chemical nature of the substituents.…”

Section: Methodsmentioning

confidence: 99%

Tautomeric Equilibria Studies by Mass Spectrometry

Allegretti¹,

Schiavonni²,

Castro

et al. 2008

Nat Prec

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Tautomerism in organic chemistry has been extensively studied in condensed phase by spectrometric methods, mainly by IR and NMR techniques. Mass spectrometry studies start 40 years ago but just recently it has been recognized the importance of the mass spectral data for the study of tautomerism in the gas phase.Mass spectrometry can provide valuable information in regard to tautomeric equilibria when studying mass spectra among the members of different families of organic compounds.The relevance of the mass spectral data resides on several facts but there are two that are of key importance:1- Mass spectral fragmentation assignments should be tautomer specific since the corresponding abundances ratios are supposed to be correlated to the keto/enol contents.2- Ionization in the ion source is supposed to have no effect on the position of the equilibrium so that the results reflect the tautomers content in the gas phase previous to ionization.Some of the carbonylic compounds do not exhibit noticeable tautomerism so the fragment abundances assigned to the enol form is very low or not measurable. Since enolization is more noticeable in the case of thio-derivatives (which correlates adequately with the oxygenated analogues), the study of their mass spectra is an interesting choice to reach some degree of generalization. In addition, experimental findings are supported by semiempirical theoretical calculations, which probed to be adequate not only for supporting tendency correlations among the members of a compound family but also to calculate heats of tautomerization in gas phase.Reports using mass spectrometry for tautomerism are becoming less common. One of the reasons is that now it would appear that the interpretation of MS results is not as straightforward as it was once believed, even though in a recent review it was written that: “Mass spectrometry is the most informative and practical method for studying and identifying tautomers in the gas phase” [1]. In fact, mass spectrometry seems to be very informative for studying and identifying tautomers, because in this case external factors like solvents, intermolecular interactions, etc., can be excluded by transferring the tautomeric system into gas phase, where the process becomes truly unimolecular [1].This review covers the study of Tautomerism by Mass Spectrometry in the last four decades.

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Section: Methodsmentioning

confidence: 99%

Tautomeric Equilibria Studies by Mass Spectrometry

Allegretti¹,

Schiavonni²,

Castro

et al. 2008

Nat Prec

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“…The electron impact (EI) mass spectra of 4-aminosubstituted 1,2-dihydro-1-methylpyrimidin-2(1H)-ones were reported in [55]. Decomposition of their molecular ions significantly depends on the substituent nature.…”

Section: Studies On Different Compound Seriesmentioning

confidence: 99%

Mass spectrometry as a tool for studying tautomerism

et al. 2008

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“…[14][15][16] To the best of our knowledge, electron impact ionization (EI) mass spectrometry has been extensively applied to structural elucidation of the 1,3-oxazines and pyrimidinones. [17][18][19][20][21][22][23][24][25][26] Besides, a few other ionization methods, such as chemical ionization (CI), electrospray ionization (ESI), have also been reported. [27][28][29][30] Although ESI usually brings out a quasi-molecular ion with little fragmentation information, it provides great advantage in a liquid chromatography/mass spectrometry (LC/MS) technique, which is widely used in high throughput screening combinatorial chemistry.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation Study of 2‐Amino‐4H‐1,3‐oxazines and Octahydro‐4‐phenyl‐2H‐pyrano[2,3‐d]pyrimidin‐2‐ones: Identification of Heterocyclic Six‐membered Ring in Three‐component Reactions

Tai

Wan

et al. 2009

Chin. J. Chem.

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The fragmentation behavior of ten 2-amino-4H-1,3-oxazines and seven octahydro-4-phenyl-2H-pyrano[2,3-d]-pyrimidin-2-ones was investigated by electrospray ionization tandem mass spectrometry (ESI-MS n ). When the precursor ions were protonated oxazines, two predominant fragmentation pathways were observed with elimination of CH 2 N 2 and HCNO, respectively. The product ion [M＋H-60] ＋ could be observed from both pathways. While in the type of pyrimidin-2-ones, only direct loss of 60 Da (urea) could be observed. The fragmentation pathways were investigated by high-resolution mass spectrometry and deuterium-labeling experiments, and the characteristic fragmentations presented here could be convenient for future identification of resembled derivatives, especially in high throughput screening combinatorial chemistry.

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Mass spectrometry of pyrimidine derivatives: Electron impact‐induced decomposition of molecular ions of 4‐amino‐substituted and 4‐amino‐disubstituted 1,2‐dihydro‐1‐methylpyrimidin‐2‐ones

Cited by 6 publications

References 14 publications

Tautomeric Equilibria Studies by Mass Spectrometry

Tautomeric Equilibria Studies by Mass Spectrometry

Mass spectrometry as a tool for studying tautomerism

Fragmentation Study of 2‐Amino‐4H‐1,3‐oxazines and Octahydro‐4‐phenyl‐2H‐pyrano[2,3‐d]pyrimidin‐2‐ones: Identification of Heterocyclic Six‐membered Ring in Three‐component Reactions

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