5-CYANO-6-ARYLURACIL AND 2-THIOURACIL DERIVATIVES AS POTENTIAL CHEMOTHERAPEUTIC-AGENTS .4.

A series of 5-cyano-6-aryluracils and 2-thiouracils 1a-h was prepared and alkylated to 1,3-dialkyluracils 2a-d and 2-alkylthiouracils, 3, 4 and 6, by electrophilic substitution with alkyl halides. Reaction of 1b with dibromoethane and 1,3-dibromopropane gave the corresponding bicyclic products, 7-aryl-6-cyano-2,3-dihydrothiazolo[3,2-.alpha.]pyrimidin-5-ones 5a,b and 8-aryl-7-cyano-3,4-dihydro-2H-pyrimido[2,3-b][1,3]thiazin-6-ones 5c-g. Nucleophilic substitution on 6 with hydrazine led to 7 which on refluxing with formic acid gave 5-aryl-6-cyano-8-methyl-s-triazolo[3,4-b]pyrimidin-7-ones (9), while with acetic and propionic acids only 2-acylhydrazino-3-methyl-4-oxo-5-cyano-6-arylpyrimidines 8a,b were isolated. The hydrazine 7 undergoes cyclization with acetylacetone and methyl dimethylmercaptoacrylate providing 2-(pyrazol-1-yl)-3-methyl-4-oxo-5-cyano-6-substituted pyrimidines 10 and 11. Some of the compounds were screened for antibacterial-, antifungal- and antiviral activities and a few of them showed significant chemotherapeutical activities.