title: Fragmentation pathways of 2-substituted pyrrole derivatives using electrospray ionization ion trap and electrospray ionization quadrupole time-of-flight mass spectrometry.
abstract: BACKGROUND
  Pyrrole derivatives are of considerable importance and are present in a wide range of natural products and used extensively in drug discovery. Fragmentation pathway studies play an important role in the structural identification of pyrrole derivatives. As a part of our ongoing work on heterocycles, fragmentation pathways of 2-substituted pyrrole derivatives were investigated by mass spectrometry (MS).
  
  
  METHODS
  Twelve pyrrole derivatives were synthesized and analyzed. Low-resolution fragmentation ions of all the compounds were generated by ion trap mass spectrometry (ITMS(n) ) with an electrospray ionization (ESI) source in positive mode. Hybrid quadrupole time-of-flight mass spectrometry (QTOFMS) was used to determine the elemental compositions of the resultant product ions.
  
  
  RESULTS
  The side-chain substituents at the 2-position influence the fragmentation pathways. Typical losses of H2 O, aldehydes and pyrrole moieties from the [M + H](+) ion are observed for the compounds with side chains bearing aromatic groups at the 2-position of the pyrrole. However, losses of H2 O, alcohols and C3 H6 are the main cleavage pathways for compounds 6 and 12 with nonphenyl-substituted side chains at the 2-position.
  
  
  CONCLUSIONS
  Typical fragmentation mechanisms of 2-substituted pyrrole derivatives are proposed and elucidated based on the observations of ITMS(n) and QTOFMS spectra. The results showed that the fragmentation pathways were remarkably influenced by the side-chain substituents at the 2-position of pyrrole. This investigation should have value in the structural identification of this series of molecules or compounds with similar structures.
authors.affiliation: Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, 310014, P.R. China.
authors.forename: Xianrui
authors.initials: X
authors.lastname: Liang
authors.forename: Zili
authors.initials: Z
authors.lastname: Guo
authors.forename: Chuanming
authors.initials: C
authors.lastname: Yu
mesh_terms: D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D011758:Pyrroles / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007477:Ions; D011758:Pyrroles