The mass spectra of some naturally‐occurring 3,4‐dialkoxy furocoumarins and their nor‐derivatives

Abstract

<jats:title>Abstract</jats:title><jats:p>The mass spectral fragmentations of several naturally‐occurring 3,4‐dialkoxy furocoumarins from the <jats:italic>Halfordia</jats:italic> species and their <jats:italic>nor</jats:italic>‐derivatives have been studied using deuterium labelling and metastable analysis. Halfordin (I), isohalfordin (VI) and halkendin (X) show a common major breakdown pathway involving initial loss of a methyl radical from the 3‐methoxy group followed by expulsion of CO, then loss of C<jats:sub>2</jats:sub>H<jats:sub>3</jats:sub>O, the latter fragment containing the methyl group from the 4‐position.