Electron impact mass spectra of isobenzofurans,isonaphthofurans and some of their Diels–Alder adducts

The mass spectra of a wide variety of substituted isobenzofurans (IBF) have been studied by the direct examination of stable IBFs and IBF ions formed in the retro-Diels–Alder cleavage of oxabicyclo adducts. In general, the fragmentation patterns observed are very dependent upon the nature and position of substitution. The dimethyl acetylenedkarboxylate adducts also show additional interesting and novel fragmentation pathways that are not IBF related.