Mass spectra of trimethylsilyl derivatives of naturally occurring flavonoid aglycones and chalcones

Electron impact mass spectra of the trimethylsilyl derivatives of a series of flavonoid aglycones and chalcones are reported. The spectra show prominent ions arising from fragmentation of the trimethylsilyl (TMS) groups. Inter-actions between adjacent TMS groups, and between TMS groups in the 3- or 5-position (6′-position for the chalcones) and the C-ring carbonyl, yield structurally significant ions. Few fragments associated with the retro-Diels-Alder cleavage of the C-ring characteristic of the underivatized compounds, are observed. The TMS derivatives thus provide complementary information for the identification of flavonoid aglycones and chalcones in biological systems.