Mass Spectra of New Heterocycles: XIX. Electron Impact and Chemical Ionization Study of 2,7-Dihydrothiopyrano[2,3-b]pyrrol-6-amines

Abstract

Fragmentation of N, N-dialkyl-7-[alkyl and 2-(vinyloxy)ethyl]-2,7-dihydrothiopyrano[2,3-b]pyrrol-6-amines under electron impact (70 eV) and chemical ionization (methane as reactant gas) has been studied. The electron impact ionization of these compounds gives rise to stable molecular ions which decompose according to two main pathways. The major pathway involves cleavage of the N⁷—C_Alk bond with elimination of the alkyl radical. The minor pathway is expulsion of alkyl radical from the amino nitrogen atom in the 6-position. The chemical ionization of 2,7-dihydrothiopyrano[2,3-b]pyrrol-6-amines characteristically involves protonation and electrophilic addition processes with the most abundant ion being [M + H]⁺.