Mass Spectra of New Heterocycles: XXII. Electron Impact and Chemical Ionization of 1-Alkyl(cycloalkyl, alkoxyalkyl)-5-[(alkyl, allyl, benzyl)sulfanyl]-1H-pyrrol-2-amines

Abstract

Fragmentation of 1-alkyl(cycloalkyl, alkoxyalkyl)-5-[(alkyl, allyl, benzyl)sulfanyl]-1H-pyrrol-2-amines under electron impact (70 eV) and chemical ionization (with methane as reactant gas) has been studied for the first time. All the examined compounds under electron impact generated the molecular ion [M]+· (Irel 5–90%) whose primary fragmentation involved mainly cleavage of the C–S bond in the SR4 substituent with elimination of R4 radical (except for 1-isopropyl- and 1-cycloalkyl-1H-pyrrol-2-amines). The main pathway of the decomposition of 1-isopropyl(cycloalkyl)-N,N-dimethyl-5-[(methyl, allyl)sulfanyl]-1H-pyrrol-2-amines was cleavage of the C–N bond with both elimination of the R1 radical from the pyrrole nitrogen atom and fragmentation of the pyrrole ring through elimination of imine (or aziridine) molecule and formation of odd-electron [M – NR1]+· radical cation. Chemical ionization of the title compounds involved protonation, charge exchange, and electrophilic addition processes and elimination of Me (Et) and SMe (SEt) radicals from the [M + H]+ ions.