Electron impact-induced fragmentation of 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (original) (raw)
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Journal of Heterocyclic Chemistry, 1985
The mass spectral fragmentation patterns of ten 7-(o- and p-R-benzylidene)-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles, I, obtained by electron impact have been studied. All the spectra analyzed contain molecular ions and the principal fragmentation routes take place either from the molecular ion, or from (M+-1) ion. Likewise, our investigation of the mass spectra of these compounds revealed interesting relationships between the substitution pattern in the framework of I and the fragmenation pathways.
Electron impact-induced fragmentation of15N-labelled 1,2,4-triazoles
Organic Mass Spectrometry, 1992
The electron impact-induced fragmentation patterns of 3,5-diphenyl-lH-l,2,4-[ 4-"N 1 triazole, 4-ethyl-3,5diphenyl-4H-1,2,4-[ 4-"N] triazole, l-ethyl-3,5-dipbenyl-lH-1,2,4-[ 4-"N 1 triazole and the corresponding unlabelled compounds were established from exact mass measurements and from metastable ion evidence. Evidence for two fragmentation mechanisms was established for the formation of the m/z 104 peak in the spectrum of the 4-ethyl compound. Only the 1-alkylated triazole exhibited an intense peak at m/z 131. Major peaks at m/z 221 (222) and 118 are characteristic of the investigated triazoles.
An unusual electron impact induced fragmentation of methylbenzofurazans
Organic Mass Spectrometry, 1976
The electron impact mass spectra of 4and 5-methylbenzofurazans exhibit an ion corresponding to the loss of CHO from the molecular ion. Loss of NO from the molecular ion is quite unimportant, in contrast to the behaviour of benzofurazan and some other substituted benzofurazans, in which loss of NO is the dominant process.
AM1 and electron impact mass spectrometry study of the fragmentation of 4-acyl isochroman-1,3-diones
Bulletin of the Chemical Society of Ethiopia, 2012
Recently, in electron impact mass spectrometry (EIMS), it has been found a good correlation between the fragmentation processes of coumarins and the electronic charges of the atoms of their skeleton. In this paper, the same analytical method has been applied to 4-acyl isochroman-1,3-diones, whose mass spectra had been studied earlier and described for the very first time from our laboratory. Results obtained are in good agreement with the last study.
Organic Mass Spectrometry, 1989
A study of the electron ionization mass spectra of certain azadispiro(S.1.5.2)pentadec-9-ene-7,lS-diones and azadispiro(4.1.4.2)t1idec-&ene-6,13-diones and their derivatives has revealed that these molecules undergo fragmentation primarily by two routes, viz. loss. of CO and elimination of the substituent on the pyrrolidine nitrogen. Under positive ionization conditions loss of CO is the predominant process in the diones as it releases the ring strain, while in the 6-or 7-0ls loss of the substituent on nitrogen is the favoured pathway. The further decomposition pathways of these primary fragments [M-COj+' and IM-OR3]+ have been delineated with the help of high-resolution mass measurements, D,O exchange and metastable spectra. These compounds give very simple negative ion spectra showing only [M-OR3]and (NCOl' ions except the N-hydroxy compounds which show (M-HI-ions as well.
Rapid Communications in Mass Spectrometry, 2000
A series of 3,7-dialkyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones was prepared, and the details of their fragmentation under electron ionization (EI) were elucidated. The molecular ions of each compound under consideration were quite abundant in their EI spectra. Full-scan spectra exhibited a number of fragment ions which were clearly assigned using MS/MS and accurate mass measurements. The basic fragmentation of 3,7-dialkyl-1,5-diphenylbispidinones was due to the cleavage of C(1)-C(2) bond followed by a hydrogen migration similar to an odd-electron McLafferty rearrangement. Alternatively, the C(1)-C(2) bond cleavage was followed by the elimination of an imine molecule, Alk-N==CH 2 . Further fragmentation resulted in ions at m/z 234 and 103, present in the spectra of all the compounds under study. The fragmentation pathways proposed in this paper are based on the substituent shifts, accurate mass measurements and collision-induced dissociation spectra of selected ions. The results of the present work can be useful in selecting the fragment ions suitable for identification and quantitation of bispidinones in biological matrices.