Mass spectrometry of bis-quinolizidine alkaloids: 2- and 17-alkyl-substituted derivatives of sparteine and lupanine.

The mass spectral fragmentations of 2-methylsparteine (1), 2, 17-dimethylsparteine (2), 2-methyl-17-isopropylsparteine (3), 2-methyl-17-oxosparteine (4), 2-oxo-17-methylsparteine (17-methyllupanine) (5) and 2-oxo-17-isopropylsparteine (17-isopropyllupanine) (6) were investigated. Fragmentation pathways, whose identification was assisted by accurate mass measurements and a correlation between the abundances of the M(+.) and selected fragment ions of the investigated compounds, are discussed. The data obtained create the basis for distinguishing the structural isomers and metamers.