Reaction of 5-amino-4-formyl-3-methyl(or phenyl)-1-phenyl-1H-pyrazoles with active methylene compounds: Synthesis of fused heterocyclic rings

A convenient one-pot synthesis of fused heterocyclic ring systems, pyrazolo[3',4':5,6]pyrido[2,3-d]pyrimidines 3a-d, dipyrazolopyridines 4a-b, pyrazolo[3,4-b]quinolines 5a-b and 6a-b and pyrazolo[3,4-b]pyridines 7a-b, has been achieved by condensation of 5-amino-4-formyl-3-methyl(or phenyl)-1-phenyl-1H-pyrazoles 2a-b with 1,3-diaryl-4,6-dioxo-2-thioxo-hexahydropyrimidines, 3-methyl-1-phenyl-1H-2-pyrazolin-5-one, dimedone,cyclohexanone and 3-acetylpyridine, respectively.