Synthesis and mass spectrometry of 4-oxo-4,5,6,7-tetrahydroindole and 4-oxo-4,5,6,7-tetrahydrobenzofuran derivatives

We describe in this communication the synthesis and mass spectrometry of some l-aryl-2-phenyl-4-oxo-4,5,6,7-tetrahydroindole (IIIb, IVab-VIIIab, VIIIb, IXb) and 2-phenyl-4-oxo-4,5,6,7-tetrahydrobenzofuran derivatives (IIab). The fragmentations of these compounds are characterized by selectivity and the absence of any primary fragmentations involving substituents of the aryl rings. It is suggested that positive charges of the molecular ions of compounds II? IX are localized in the region of the carbonyl group and the conjugated double bond of the heterocycle.