Synthesis and physicochemical characterization of fluorescent (E)‐2‐stilbenyloxyalkylthiouracils and isomer differentiation using EIMS

Twelve new fluorescent (E)‐2‐stilbenyloxyalkylthiouracils and 6‐methyluracils 5a‐51 were prepared. EI induced mass spectral fragmentation of these compounds was investigated. Fragmentation pathways are proposed on the basis of accurate mass and metastable transition measurements. Correlation between the intensities of the M⁺ and the selected fragment ions of these compounds is discussed. The data obtained permit a distinction of the metamers. The ¹H and ¹³C NMR spectra of these compounds were assigned unambiguously using a combination of heteronuclear (HETCOR) spectra and the chemical shifts. The data derived from these spectra can be used to differentiate the isomers.