Mass spectra of isosteviol derivatives: I. Fragmentation of isosteviol derivatives having a Schiff base fragment on C4 under electron impact

Abstract

The main fragmentation pathways of the molecular ions of isosteviol (ent-16-oxobeyeran-19-oic acid) derivatives having a Schiff base fragment on C4 under electron impact include expulsion of CO molecule and methyl radical, cleavage of the C4-N bond with proton migration to the nitrogen atom, and dissociation of come bonds in the A and B rings of the tetracyclic skeleton. © 2009 Pleiades Publishing, Ltd