Electrospray ionization mass spectra of phosphacoumarin derivatives

Phosphacoumarins and their 4-O-methylsulfonate derivatives, as the analogues of the coumarins with many biological activities, were synthesized, their fragmentation pathways were investigated by electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS), and some characteristic fragment ions were observed by losing ethylene, water, CO, HPO2, HPO3, CH3SO2 or CH3SO2H from the precursors.