Synthesis of Potentially Biologically Active Fused Polyheterocycles Containing a Pyrimidine Unit

A number of new fused polyheterocyclic compounds were synthesized on the basis of 2-amino-6-sulfanylpyrirnidin-4(3H)-one. In particular, reactions of 2-amino-6-suffanylpyrirnidin-4(3H)-one with cinnamic acids, aroyl isothiocyanate, and acetic anhydride afforded imidazo[1,2-a]thieno[2,3-d]pyrimidine, [1,3]thiazino[6′,5′: 4,5]pyrimido[1,2-a][1,3,5]triazine, and imidazo[1,2-a]tWeno[2,3-d]pyrimidine derivatives, respectively. The alkylation of 2-amino-6-smfanylpyrirnidin-4(3H)-one with benzyl chloride gave 3-benzyl-6-(benzylsulfanyl)-2-imino-2,5-dihydropyrimidin-4(3H)-one which was converted to [1,3]thiazolo[5,4-d][1,2,4]triazolo-[4,3-a]pyrimidine, imidazo[1,2-a]pyrimidine, dihydropyrimido[4,5-b]quinoline, imidazo[1,2-a]pyrrolo[2,3-d]-pyrimidine, and benzo[g]imidazo[2,1-b]pteridine derivatives via reactions with nitrous acid, ethyl chloroacetate, and aniline (followed by treatment with carbon disulfide, cinnamic acid, or sodium nitrite in acetic acid). 2-Amino-3,4-dihydropyrimidin-6-sulfonic acid was obtained by oxidation of the same substrate with hydrogen peroxide in alkaline medium. Some of the synthesized compounds showed antimicrobial activity.