Synthesis of Pyrimidine, Thiazolopyrimidine, Pyrimidotriazine and Triazolopyrimidine Derivatives and their Biological Evaluation

Pyrimidin-4-one-2-thione (3) was synthesized via the reaction of thiourea (1) with ethyl benzoylacetate (2) and was taken as a starting material for the present study via its reactions with the halogen-containing reagents 6a-d and lOa-c to give the corresponding thiazolopyrimidines 8, 9 and 12a-c. The 2-hydrazino derivatives 5 were synthesized either via the reaction of 3 or 4 with hydrazine hydrate. Compound 5 reacted with 6a-c and lOa-c to give the corresponding pyrimidotriazines 17a-c and 19 respectively. Also, compound 5 reacted with the active methylene-containing reagents 13 and 2a,b to give the corresponding 2-pyrazolopyrimidines 15 and 22a,b respectively. On the other hand, the triazolopyrimidines 21a,b and 30a,b were also obtained via the reaction of 5 with each of formic acid, acetic anhydride, ethyl chloroformate and carbon disulfide respectively. Some of the newly synthesized heterocyclic derivatives were tested for their biological activity