Electron Ionization-Induced Mass Spectral Study of 5-Methylenecarboxy (5-Methylenecarbonylalkoxy)-2-Thio-(2-Alkoxycarbonylalkylthio)Uracils and 3-Oxothiazolo-[3,2-a]-Pyrimidine-6-Methylenecarbonylalkoxy-5-Ones

Abstract

Electron ionization (EI) mass spectral fragmentation of 2-thio-5-methylenecarboxy (5-methylenecarbonylalkoxy)uracils and their derivatives, five new 2-alkoxycarbonylalkylthio-5-methylenecarboxy (5-methylenecarbonylalkoxy)uracils and three new 3-oxothiazolo-[3,2- a]-pyrimidine-6-methylenecarbonylalkoxy-5-ones are investigated. Fragmentation pathways whose elucidation is assisted by accurate mass measurements and metastable transitions are established. The correlations between the abundances of the selected fragment ions and the molecular ions of investigated compounds are discussed. The data obtained create the basis for differentiating structural isomers and can be used for distinction of the compounds investigated from the series of 2- (or 4-) alkoxycarbonylalkylthiouracils, 2-alkoxycarbonylalkylthio-6-carboxyuracils and 1-alkoxycarbonylalkyluracils from their isomers and metamers.