Mass Spectra of New Heterocycles: XXI. Study of Alkyl [(5-Amino-1H-pyrrol-2-yl)sulfanyl]acetates by Electron and Chemical Ionization Mass Spectrometry

The fragmentation of previously inaccessible alkyl [(5-amino-1H-pyrrol-2-yl)sulfanyl]acetates under electron (70 eV) and chemical (reactant gas methane) ionization conditions was studied for the first time. Under electron ionization, all the studied compounds form a molecular ion (Irel 7–100%), the main primary fragmentation pathway of which is associated with the C–S bond cleavage in the sulfanyl group and elimination of the ester fragment (R4OCOCH2) in the form of a radical. The chemical ionization of alkyl [(5-amino-1H-pyrrol-2-yl)sulfanyl]acetates is characterized by protonation, recharging, and electrophilic addition. The base peak belongs to an [M + H]+ ion. Chemical ionization is accompanied by the elimination of an R4OCOCH2 radical from the M+• and [M + Et]+ ions and an R4OCOCHS molecule from the M+• and [M + H]+ ions.