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Mass spectrometric fragmentation pathways of isotope labeled 2,5-disubstituted-1,3,4-oxadiazoles and thiadiazoles

2003; Elsevier BV; Volume: 231; Issue: 1 Linguagem: Inglês

10.1016/j.ijms.2003.09.014

1873-2798

Rafał Frański, Błażej Gierczyk, Grzegorz Schroeder,

Chemical Reactions and Mechanisms

Abstract The mass spectrometric decomposition of protonated, lithiated and methylated (quaternary derivatives) 2-(4′-methoxy)phenyl-5-phenyl-1,3,4-oxadiazoles, containing 13 C atom at 5 position of oxadiazole ring as well as its thia correspondent is discussed. The electron-donor properties of C-4′ substituent favor cationization of N(3) atom and as a consequence, the losses of HNC(2)O, LiNC(2)O, CH 3 NC(2)O molecules are favored over HNC(5)O, LiNC(5)O, CH 3 NC(5)O molecules. Analogous results have been obtained for HNCS and CH 3 NCS elimination from thiadiazole.