ELECTRON IONIZATION-INDUCED LOSS OF A METHYL RADICAL FROM CLOPROPYL-4-SUBSTITUTED-1,2,3,6-TETRAHYDROPYRIDINE DERIVATIVES

The electron ionization mass spectra of clopropyl-4-substituted-1,2,3, 6-tetrahydropyridine derivatives are characterized by a base peak corr esponding to [M-15](+). Evidence is presented to support a fragmentati on process involving an initial cyclopropyl ring opening of the parent cyclopropylaminyl radical cation followed by intramolecular transfer of a hydrogen atom from the ring carbon atoms ct to nitrogen to the pr imary carbon-centered radical and finally a fragmentation step proceed ing by loss of a methyl radical and formation of a stable N-ethenyldih ydropyridinium ion, the [M-15](+) fragment. (C) 1997 American Society for Mass Spectrometry.