title: Electron ionization mass spectra of aryl- and benzyl-substituted 2,3-dihydroimidazo[1,2-a]pyrimidine-5,7(1H,6H)-diones.
abstract: The electron ionization mass spectra of the 1-phenyl-, 1-benzyl- and 6-benzyl-1-phenyl-2,3-dihydroimidazo[1,2-a]pyrimidine-5,7(1H,6H)-dione derivatives were recorded at 70 eV to find out the effects of substituents on their fragmentations. Fragmentation pathways were studied using B/E and B(2)/E scans. Some fragmentations involved the loss of C(3)HO(2) or carbon suboxide. The possibility of keto-enol tautomerism was also studied. For comparison selected compounds were studied using (1)H and (13)C NMR spectroscopy to reveal the presence of possible tautomerism. Some ions including [M-OH](+) and [M-HCO](+) and NMR results indicate that the enol form is predominant both in the gas and in the liquid phase.
authors.affiliation: Department of Chemistry, University of Turku, FI-20014 Turku, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Martiskainen
authors.forename: Henri
authors.initials: H
authors.lastname: Kivelä
authors.forename: Dariusz
authors.initials: D
authors.lastname: Matosiuk
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Szacon
authors.forename: Marzena
authors.initials: M
authors.lastname: Rzadkowska
authors.forename: Kalevi
authors.initials: K
authors.lastname: Pihlaja
mesh_terms: D007477:Ions; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011743:Pyrimidines / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007477:Ions; D011743:Pyrimidines