Mass spectra of new heterocycles: XV. Fragmentation of 1-substituted 3-alkoxy-2-(propargylsulfanyl)- and 3-alkoxy-2-(allenylsulfanyl)-1H-pyrroles under electron impact

The electron impact mass spectra of 1-R-substituted 3-alkoxy-2-(propargylsulfanyl)- and 3-alkoxy-2-(allenylsulfanyl)-1H-pyrroles (R = Me, i-Pr, s-Bu, Ph) have been studied for the first time. These compounds give rise to stable molecular ions whose primary fragmentation follows three competing pathways: cleavage of the C–O bonds with expulsion of alkyl radical, cleavage of the C–S bonds with formation of [M–C3H3]+ ions, and cleavage of the C–N bonds with synchronous hydrogen transfer to give odd-electron [M–CnH2n]+ · ion. The main fragmentation pathway of 2-(propargylsulfanyl) derivatives is cleavage of the C–S bond with formation of [M–C3H3]+ ion.