Mass spectrometry of onium compounds—VI: Pyrimidinium oxides

Abstract

AbstractThe 5‐methyldihydrothiazolo (3,2‐c) pyrimidinium cation is evaporated as the corresponding anhydro base. In competition with anhydro base formation the 8‐ethoxy derivative eliminates ethyl bromide to give the corresponding betaine. The latter appears to be electronically rearranged and evaporated as a covalent valence isomer. The 3‐carboxy derivative investigated suffered decarboxylation and ring opening to a vinyl thione. In the absence of a pyrimidyl methyl group the thiazolo ring was attacked by the anion.The electronically induced fragmentations are discussed and used to deduce the structures of the pyrolytic products.