Mass spectrometry of 3‐oxothiazolo[3,2‐a] and [3,2‐c]pyrimidin‐5‐ones. Correlation of the intensities of the M^+. and the selected fragment ions

Abstract

The mass spectral fragmentation of eight new 3‐oxothiazolo[3,2‐a] and [3,2‐c]pyrimidin‐5‐ones were investigated. Fragmentation pathways are proposed on the basis of accurate mass and metastable transition measurements. The correlation between the intensities of M+. and the selected fragment ions of these compounds is discussed. The data obtained created the basis for distinguishing isomers and metamers.

Electron impact induced mass spectral study of 2- and 4-ethoxycarbonylalkylthio-5-bromo-6-methyluracils

“…[1][2][3] The differences in mass fragmentation pathways of 2-and 4-alkylthiouracils, 4-6 2-and 4-alkoxycarbonylalkylthiouracils, 7,8 2-and 4-benzylthiouracils, 9 2and 4-(E)-stilbenyloxyalkylthioura-cils, 10 as well as 3-oxothiazolo-[3,2-a]-and- [3,2-c]pyrimidin-5-ones, 11 have been studied previously in our laboratory. [1][2][3] The differences in mass fragmentation pathways of 2-and 4-alkylthiouracils, 4-6 2-and 4-alkoxycarbonylalkylthiouracils, 7,8 2-and 4-benzylthiouracils, 9 2and 4-(E)-stilbenyloxyalkylthioura-cils, 10 as well as 3-oxothiazolo-[3,2-a]-and- [3,2-c]pyrimidin-5-ones, 11 have been studied previously in our laboratory.…”

Electron ionization induced mass spectral study of 2‐alkylthio‐ and 4‐alkykthio‐5‐bromouracils

“…15,16 Electron ionization mass spectrometry (EI-MS) was used to determine the location of the sulphur atom in the uracil ring or the positioning of a substituent on the nitrogen atoms N-1 or N-3. 17,18 The correlation between selected fragment ions and molecular ion abundance in benzylthiouracils, 19 2-alkylthiouracils, 20 and thiazolo-[3,2-a]-and [3,2-c]pyrimidin-5-ones 21 has been thoroughly studied in our laboratory. The fragmentation of 2-and 4-thio-5-bromouracils alkylated on the sulphur atoms has not, however, been studied.…”

Letter: Electron-Impact Mass Spectrometry in Analysis of Isomeric Alkoxycarbonylalkylthiouracils—A Correlation of M+• Intensities and Selected Fragment Ions

“…[1][2][3][4][5][6][7][8][9][10][11] The position of the uracil ring thiation of 2-or 4-substituted compounds may be deduced on the basis of the presence and intensity of selected fragment ions. [12][13][14][15][16][17][18] A correlation between the structures and intensities of M +• and the selected fragment ions of benzylthiouracils, 18 2-alkylthiouracils, 19 thiazolo- [3,2-a] and [3,2-c]-pyrimidin-5-ones 20 has been studied in our laboratory. As a continuation of the study I would like to find out whether it is possible to differentiate 2and 4-alkoxycarbonylalkylthiouracils (Figure 1), i.e.…”

“…In other cases a 3-5% difference between values of relative intensity of molecular and fragment ions can be considered statistically significant. The mass spectral fragmentation of 2-alkoxycarbonylalkylthiouracils (1-8, 11-13, 15) and 4-alkoxycarbonylalkylthiouracils (17)(18)(19)(20)(21)(22)(23)(24)(25)27) was investigated previously in our laboratory. 16,17 The principal mass fragmentation pathways of new 2-and 4-alkoxycarbonylalkythiouracils (9, 10, 14, 16, 26, 28-32) are similar to those of the other 2-and 4alkoxycarbonylalkylthio analogues.…”