Synthesis of novel disubstituted pyrazolo[1,5-a]pyrimidines, imidazo[1,2-a]pyrimidines, and pyrimido[1,2-a]benzimidazolescontaining thioether and aryl moieties

Article abstract of DOI:10.1002/hlca.201100495

A series of novel 6-[(1,3,4-thiadiazol-2-yl)sulfanyl]-7-phenylpyrazolo[1,5- a]pyrimidines, 5-phenyl-6-[(1,3,4-thiadiazol-2-yl)sulfanyl]imidazo[1,2-a] pyrimidines, and 2-phenyl-3-[(1,3,4-thiadiazol-2-yl)sulfanyl] pyrimido[1,2-a]benzimidazoles have been synthesized in four steps starting with 2-hydroxyacetophenone. The intermediate 3-[(1,3,4-thiadiazol-2-yl)sulfanyl]-4H- 1-benzopyran-4-ones reacted with pyrazol-3-amines, 5-methylpyrazol-3-amine, and 1H-imidazol-2-amine, 1H-benzimidazol-2-amine via a cyclocondensation to give the title compounds in the presence of MeONa as base, respectively. The approach affords the target compounds in acceptable-to-good yields. The new compounds were characterized by their IR, NMR, and HR mass spectra.