Proximity effects in the electron impact mass spectra of aurones and related compounds

The principal ions in the electron impact mass spectra of a series of 6-methoxyaurones have been shown to be due to four separate reactions associated with proximity effects involving the phenyl group and the coumaran-one residue. A detailed study with labelled derivatives has been supplemented by a study of the vinylogue 2-cinnamylidene-6-methoxycoumaran-3-one and compounds in which the aurone phenyl group has been replaced by α-naphthyl, β-naphthyl and 9-anthryl.