Mass spectrometry of the metabolites of 2-ethyl-2,3-dihydro-5-benzofuranylacetic acid.

The electron impact induced fragmentations of the title compound, its methyl ester, its three hydroxy derivatives, namely, 3-hydroxy alpha- and beta-hydroxy, their acetyl methyl esters and its 2,3-dehydro derivative, have been studied in detail. Among the uncommon features of the observed processes were methyl acetate and C-2 and C-3 hydrocarbon expulsions and a few novel rearrangements. The ion at m/z 131 appeared as the terminal for many fragmentation sequences.