Catalyst free synthesis of fused pyrido[2,3-d]pyrimidines and pyrazolo[3,4-b]pyridines in water

A one-pot, three-component condensation reaction of an aldehyde, benzoyl acetonitrile (3-oxo-3-phenylpropane nitrile) and 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione or 3-methyl-1-phenyl-1H-pyrazol-5-amine in water to give fused pyrido[2,3-d]pyrimidines and pyrazolo[3,4-b]pyridines in high yields without any catalyst, is described.