Determination of aqueous stability and degradation products of series of coumarin dimers.

The stability in aqueous solution of five classes of coumarin dimers (I-V, compounds 1-29) was studied by HPLC-MS/MS at various pH values. The relationship between chemical structure and stability is discussed. It was found that dimeric compounds with strong electron withdrawing groups (EWGs) on the α-carbon to the bridging C-atom are stable at all pH values, whereas other derivatives undergo retro-Michael addition at rates which are also affected by the substituents on the aromatic rings.

Collision-induced dissociation of a series of coumarins studied by positive- and negative-ion electrospray triple quadrupole tandem mass spectrometry.

Aryl-substituted 4-hydroxycoumarins (1-57) were investigated by electrospray ionisation (ESI) mass spectrometry. Their fragmentation in the ion source or in the collision cell of a triple quadrupole mass spectrometer was investigated. The effect of the substituents in the aromatic ring on the fragmentation of the 4-hydroxycoumarin derivatives is shown.