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Hydrogen rearrangement and ring cleavage reactions study of progesterone by triple quadrupole mass spectrometry and density functional theory
Author(s) -
Jeilani Yassin A.,
Cardelino Beatriz H.,
Ibeanusi Victor M.
Publication year - 2011
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1931
Subject(s) - chemistry , fragmentation (computing) , density functional theory , cleavage (geology) , quadrupole , bond cleavage , ring (chemistry) , tandem mass spectrometry , triple quadrupole mass spectrometer , mass spectrometry , ion , computational chemistry , triple bond , ketene , stereochemistry , double bond , medicinal chemistry , selected reaction monitoring , atomic physics , organic chemistry , catalysis , physics , geotechnical engineering , chromatography , fracture (geology) , computer science , engineering , operating system
The fragmentation mechanisms of progesterone have been studied by triple quadrupole tandem mass spectrometry (MSMS) and density functional theory (DFT). Mechanisms leading to major product ions are proposed. The data suggest that progesterone fragments preferentially via hydrogen and other rearrangements lead to neutral losses. These fragmentations are quite complex and are preceded by σ‐bond cleavages in most cases. Four major pathways for progesterone fragmentation are proposed involving: (1) cleavage of ring B at C9C10, (2) cleavage of C6C7 bond in ring B through m / z 191, (3) two types of cleavages of ring D, and (4) ketene elimination in ring A. Pathways (1)–(3) proceed via charge‐remote fragmentations while pathway (4) proceeds via charge‐site initiated mechanism. The geometry of product ions in these pathways were optimized using DFT at the B3LYP/6‐311G(d,p) level of theory from which the free energies of the pathways were calculated. The effect that the choice of basis sets and density functionals has on the results was tested by performing additional calculations using B3LYP/6‐31G(d) and B3PW91/6‐311G(d,p). Copyright © 2011 John Wiley & Sons, Ltd.