Synthesis and Mass Spectral Fragmentation of Fused Benzopyrano [4,3-D] Pyrimidin-5-One Derivatives

H. K. Ibrahim

Faculty of Science, Suez Canal University, Ismailia (Egypt)

Reaction of 2-mercapto-4-hydroxy-5H-[1]-benzopyrano-[4,3-d]-pyrimidin-5-one (1) with ethyl chloroacetate, 1,2-dichloroethane, methyl acrylate and acrylonitrile yielded the corresponding benzopyrano-[4,3-d]-3,1-thiazolo-1[1,2-a]-pyrimidinones (3 and 5), benzopyrano-[4,3-d]-3,1-thiazino-[1,2-a]-pyrimidinetriones (7) and 2-(cyano-ethyl)thio-4-hydroxy-5H-[1]-benzopyrano-[4,3-d]-pyrimidine-5-one (8), respectively. The electron impact ionization mass spectra of compounds 2, 6 and 8 show a weak molecular ion peak and a base peak of m/z 259 resulting from cleavage fragmentation. The compounds 3 and 7 give a characteristic fragmentation pattern with a very stable fragment at m/z 244 and m/z 55, while the stable fragment of compound 5 is the molecular ion of m/z 272.

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