Ammonia chemical ionization tandem mass spectrometry in structure determination of alkaloids. I. Pyrrolidines, piperidines, decahydroquinolines, pyrrolizidines, indolizidines, quinolizidines and an azabicyclo[5.3.0]decane

CI-MS/MS of alkaloids with ammonia reagent gas and collision-induced dissociation provides unique structural information for certain mono- and bi-cyclic alkaloids. This technique was applied to solve the structures of 195C, a 4,6-disubstituted quinolizidine alkaloid found in frog skin and an ant, and 275A, a novel 3,5-disubstituted azabicyclo[5.3.0]decane found in frog skin.