Reactions of pyrimidinonethione derivatives: Synthesis of 2-hydrazinopyrimidin-4-one, pyrimido[1,2-a]-1,2,4-triazine, triazolo-[1,2-a]pyrimidine, 2-(1-pyrazolo)pyrimidine and 2-arylhydrazonopyrimidine derivatives.

6-Aryl-5-cyano-4-pyrimidinon-2-thione derivatives1a-c reacted with ethyl iodide to give the corresponded 2-S-ethylpyrimidin-4-one derivatives2a-c. Compounds2a-c was, in turn, reacted with hydrazine hydrate to give the sulfur free reaction products,3a-c. These reaction products were taken as the starting materials for the synthesis of several newly synthesized heterocyclic derivatives. Reactions with several halogenated ketones, esters, chloroacetic acid and chloroacetamide give pyrimidotriazines8, 12 and15 while their reactions with formic acid, acetic acid and carbon disulfide gave the corresponded triazolopyrimidines17 and21. The reaction with both acetyl acetone and ethylacetoacetate gave the corresponded 2-(3', 5'-dimethyl-1'-pyrazoly) pyrimidine derivatives20a-c and24a-c respectively while the reaction with cinnamonitriles25a-h afforded the corresponded aryl hydrazopyrimidines27a-f. The structures of these reaction products were established based on both elemental analyses and spectral data studies.