Sz. Vatsadze et al., Fragmentation of 3,7-dialkyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones under electron ionization, RAP C MASS, 14(20), 2000, pp. 1949-1953
A series of 3,7-dialkyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones wa
s prepared, and the details of their fragmentation under electron ionizatio
n (EI) were elucidated. The molecular ions of each compound under considera
tion were quite abundant in their EI spectra. Full-scan spectra exhibited a
number of fragment ions which were clearly assigned using MS/MS and accura
te mass measurements. The basic fragmentation of 3,7-dialkyl-1,5-diphenylbi
spidinones was due to the cleavage of C(1)-C(2) bond followed by a hydrogen
migration similar to an odd-electron McLafferty rearrangement. Alternative
ly, the C(1)C(2) bond cleavage was followed by the elimination of an imine
molecule, Alk-N=CH2. Further fragmentation resulted in ions at m/z 234 and
103, present in the spectra of all the compounds under study. The fragmenta
tion pathways proposed in this paper are based on the substituent shifts, a
ccurate mass measurements and collision-induced dissociation spectra of sel
ected 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. Copyright (C) 2000 John Wiley gr Sons, Ltd.