Electrospray‐Ionization Mass Spectrometry. Part 2. Neighboring‐Group Participation in the Mass‐Spectral Decomposition of 4‐Hydroxycinnamoyl‐spermidines

Abstract

AbstractThe three mono substituted N‐[(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoyl]spermidines 1–3 have been studied by positive‐ion electrospray‐ionization tandem mass spectrometry (ESI‐MS/MS). Because of the neighboring‐group participation, the MS/MS of [1 + H]+ and [2 + H]+ are essentially similar, while compound 3 can be easily distinguished from 1 and 2 because of the characteristic ions at m/z 218. However, with the source collision‐induced dissociation (source‐CID) MS/MS technique, the compounds 1 and 2 can be unambiguously distinguished by the signal of the pyrrolidinium ion (m/z 72) from their daughter ion (m/z 275). The source‐CID MS/MS of the labeled compound N‐(4‐aminobutyl)‐N‐(3‐aminopropyl)‐N‐[3‐(4‐ hydroxyphenyl)prop‐2‐en[15N]amide] ([15N(4)]‐2) provide more information on the decomposition mechanisms and proved the occurrence of a partial transamidation reaction 2→1 during the measurement.