Synthesis of Potential Anticancer Agents. IV. 5, 7-Disubstituted s-Triazolo [2, 3-a] pyrimidines.

The products of the condensation of 5-amino-s-triazole (I) with ethyl malonate, ethyl cyanoacetate, and methyl ethoxycarbonyldithioacetate were proved to be respectively 5, 7-dihydroxy-, 5-hydroxy-7-amino-, and 5-hydroxy-7-mercapto-s-triazolo [2, 3-a] pyriminines (II, III, and IV). (II) was converted into the 5, 7-dichloro derivative (VI), and the reactivity of the two halogens in (VI) towards the usual nucleophilic reagents was examined. (IV) was also transformed into the 5-chloro-7-methylthio derivative (XXI), which was converted into 5-substituted 7-methylthio derivatives by nucleophilic substitution. Ultraviolet absorption spectra of 5-substituted and 7-substituted s-triazolo [2, 3-a] pyrimidines were compared.