The mass spectrometry of 4-arylquinolizid-2-ones

The fragmentation pathways of ten 4-substituted quinolizid-2-ones were established using exact mass measurement, deuterium labelling and detection of metastable transitions. The base peak for most ketones was formed by cleavage of the C-2? C-3 bond (α to the carbonyl group) and the benzylic C-4? N bond. The decompositions examined were compared with those of the Nuphar alkaloids.