Structural Exploration of Phantom Oligoguanidine from Asymmetric Diamine and Guanidine Hydrochloride

Condensation reaction of asymmetric triamine (spermidine) with guanidine hydrochloride provides a phantom structure with selective formation of rings in the repeat unit. The intermolecular condensation between amine and guanidine hydrochloride can provide either a linear structure or six- or seven-membered rings in the repeat unit by elimination of one or three molecules of ammonia, respectively, per repeat unit. The preference of formation of rings and mechanistic aspects are studied by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 1D, 2D NMR, and quantum chemical calculations.