Synthesis of pyrazolo[1,5-a]pyridines and pyrazolo[1,5-c]pyrimidines by reaction of heterocyclic amidrazones with 1,3-dicarbonyl compounds

1,3-Dicarbonyl compounds 2 react with 1-amino-2(1H)-pyridin-2-imines or 1-amino-2(1H)-pyrimidin-2-imines 1 giving new pyrazolo[1,5-a]pyridines or pyrazolo[1,5-c]pyrimidines 5 respectively by addition, oxidation and condensation. Isolation of an intermediate 3 shows that surprisingly the addition of the CH acidic 1,3 -dicarbonyl compound to position 6 of the pyrimidine 1 is the initial step.