Electron ionization mass spectra of indolenines obtained using sector and ion trap mass spectrometers

Abstract

The electron impact (EI)-induced fragmentations of 18 indolenines were studied using both double-focusing and ion trap mass spectrometers. The compounds used in this study were synthesized to provide correlations of characteristic fragment ions with specific structural differences. In 2-hydroxyindolenines the hydroxy group was involved in a major fragmentation process by interacting with the ester side chain to generate an alpha,beta-unsaturated gamma-lactone structure, with concomitant loss of the corresponding alcohol. In contrast, loss of an alkyl radical, derived solely from the 2-alkoxy group, is a major primary decomposition process for 2-alkoxyindolenines. EI-MS analyses using sector and ion trap spectrometers resulted in similar fragmentation patterns.

Unimolecular rearrangements of ketene‐O,O‐acetals and fragmentations occurring in the gas phase

“…The accurate mass measurements confirmed the composition of the fragment of interest at m / z 272.0797 for 4a (C 14 H 12 N 2 O 4 +• , − 0.4 ppm) and at m / z 264.1025 for 4c (C 17 H 14 NO 2 + , 1.1 ppm). Besides the dominant fragmentations discussed above, an interesting alternative fragmentation pathway occurs for all the studied compounds 4a – e which could be connected with the cleavage of the NC carbamate bond22, 23 to give the [M − 59] + ion (Table 1). The elemental compositions of these ions were also confirmed using accurate mass measurements, which afforded relative errors within the range − 0.4 to 1.6 ppm.…”