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Mass Spectral fragmentation patterns of heterocycles. V . Electron impact promoted mass spectral fragmentation of indolo[1,7‐ ab ][1]benzazepine and Some of its Derivatives
Author(s) -
Vishwakarma L. C.,
Hallberg A.,
Martin A. R.
Publication year - 1983
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570200513
Subject(s) - chemistry , fragmentation (computing) , ion , mass spectrum , electron ionization , metastability , spectral line , carbon monoxide , stereochemistry , analytical chemistry (journal) , organic chemistry , physics , astronomy , computer science , catalysis , ionization , operating system
The fragmentation patterns of 1,2,6,7‐tetrahydroindolo[1,7‐ ab ][l]benzazepin‐1‐one ( 1 ), 6,7‐dihydroindolo‐[1,7‐ ab ][l]benzazepine ( 2 ) and indolo[1,7‐ ab ][1]benzazepine ( 3 ) on electron impact have been examined. Loss of carbon monoxide to form the base peak at m/e 207 and loss of CHO radical to give m/e 206 consititute the major fragmentation pathways for 1. The moleclar ions ( M + ) are abundant for each of the compounds; observed as the second most intense peak for 1 (85% relative intensity) and the base peaks for 2 and 3 . The spectrum of 2 is characterized by intense M‐1 and M‐2 ions and by the presence of a M‐15 ion (m/e 204) of moderate intensity (11.4%). In all other respects the spectra of 2 and 3 are strikingly similar. The M‐15 ion from 2 , assigned the heteroaromatic pyrroloacridinium structure, is also formed in the spectrum of 1. A second heteroaromatic ion at m/e 191, common to the spectra of 1 , 2 and 3 , is believed to have the pyrrolocarbazol‐ium structure. Metastable ion transitions and exact mass measurements support most of the proposed fragmentation pathways and structural assignments.