Rearrangement with formamide extrusion in the electrospray mass spectra ofaminoacylbenzylamines

Several aminoacylbenzylamines and their analogs were synthesized and analyz ed by electrospray ionization mass spectrometry together with high-resoluti on and tandem mass spectrometric techniques. Fragment ions ([M + H - CH3NO] (+)) were observed and attributed to a transfer of the benzyl group to the N-terminal amino group, leading to elimination of formamide. The proposed m echanism is supported by accurate mass measurements, and by experiments on deuterium labeling and variations of functional groups. Copyright (C) 2001 John Wiley & Sons, Ltd.