The decomposition of some NG-(ω-aminoalkanoyl) argininamides, which are key intermediates for the preparation of radiolabeled and fluorescent neuropeptide Y receptor ligands, prompted us to synthesize a small series of simple 1-(ω-aminoalkanoyl) guanidines, and to investigate these model compounds for stability in alkaline buffers. The degradation of acylguanidines was monitored by time resolved UV spectroscopy. The most labile ...