M-H(+) ions in 3-alkyl substituted indoles detected by electrospray mass spectrometry

摘要

A series of six C-3 alkyl-substituted indole derivatives were investigated using electrospray, ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS). Anomalous [M-H](+) ions, were detected. Three possible pathways forming [M-H](+) were proposed. MS/MS spectra and radical, trapping experiment support direct loss of hydride anion. Notably, the positions losing the hydride, anion were different for these compounds, and were tentatively confirmed by D-labeled and MS/MS, spectra. Both steric hindrance and electronic effect might contribute the difference. (c) 2014 Elsevier B.V. All rights reserved.