Characterisation of new pyridazinofurocoumarins by electron ionisation and multiple stage tandem mass spectrometry using an ion trap mass spectrometer.

The inverse electron-demand Diels-Alder reaction between furocoumarinones and 3,6-bis(methoxycarbonyl)-1,2,4,5-tetrazine was used to give pyridazinofurocoumarins in good yields. The structural characterisation of the synthesised compounds was achieved by NMR spectroscopy. The mass spectrometric behaviour was studied under electron ionisation conditions via sequential product ion fragmentation experiments (MS(n)). This study allowed the evaluation of the role played by the methyl substituent on the benzene ring of pyridazinofurocoumarins in their fragmentation pathways.