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Electron impact mass spectral fragmentation of 3a,5‐disubstituted 1,3‐diphenyl‐3a,4,5,6‐tetra‐hydro‐3 H ‐1,2,4‐triazolo[4,3‐ a ][1,5]benzo‐diazepines
Author(s) -
Xu Jiaxi,
Zhang Qihan,
Wang Chenbo
Publication year - 2000
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/1097-0231(20001230)14:24<2339::aid-rcm170>3.0.co;2-l
Subject(s) - chemistry , cycloaddition , ion , benzonitrile , electron ionization , mass spectrometry , styrene , medicinal chemistry , radical , photochemistry , molecule , fragmentation (computing) , polyatomic ion , ionization , organic chemistry , polymer , operating system , chromatography , computer science , copolymer , catalysis
The mass spectrometric behaviour of six 3a,5‐disubstituted 1,3‐diphenyl‐3a,4,5,6‐tetrahydro‐3 H ‐1,2,4‐triazolo[4,3‐ a ][1,5]benzodiazepines has been studied with the aid of mass‐analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate (substituted) styrene molecules, aryl radicals, arylmethyl radicals or phenylnitrene (PhN:). All of the resulting fragment ions, except [M − PhN:] +· , could further undergo a reverse [2 + 3] cycloaddition. The [M − PhN:] +· ions could further lose styrene derivatives and undergo a ring enlargement rearrangement. The molecular ions also show a tendency to eliminate a phenyl radical, and the [M − Ph] + ions could eliminate styrene derivatives. The [M − R 1 CH = CH 2 ] +· ions could further lose NH 2 to yield stable tetracyclic 1,3‐diphenyl‐1,2,4‐triazolo[4,3‐ d ]phenanthridine ions, which could further lose benzonitrile, or undergo a reverse [2 + 3] cycloaddition. The molecular ions could also undergo a reverse [2 + 3] cycloaddition to produce N ‐phenylbenzonitrile imine ions and 2,4‐disubstituted 2,3‐dihydro‐1 H ‐1,5‐benzodiazepine ions, whose further fragmentations were also investigated. Copyright © 2000 John Wiley & Sons, Ltd.