A convenient route to pyridones, pyrazolo[2,3-a]pyrimidines and pyrazolo[5,1-c]triazines incorporating antipyrine moiety

Condensation of 4-aminoantipyrine with ethyl acetoacetate, ethyl benzoylacetate, and ethyl cyanoacetate furnished the corresponding ethyl 3-(1,2dihydro-1, 5-dimethyl-2-phenyl-3-oxo-3H-pyrazol-4yl)aminoacrylate and 2-cyano-N-[(1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxo-3H-pyrazol-4-yl)]acetamide derivatives. The aminoacrylates derivatives react with acetonitrile and sodium hydride to give 2-amino-6-methyl-1-(1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxo-3H-pyrazol-4-yl)-4-pyridone. Reaction of the cyanoacetamide derivative with dimethylformamide-dimethylacetal (DMF-DMA) afforded 2-cyano-N-[1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxo-pyrazol-4-yl]-2-(N,N-dimethylamino)methylene acetamide in high yield. Treatment of the latter with 5-aminopyrazole derivatives afforded the corresponding pyrazolo[2,3-a]pyrimidines. 2-cyano-N-[(1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxo-3H-pyrazol-4-yl)]acetamide also reacts with heterocyclic diazonium salts to give the corresponding pyrazolo[5,1-c]-1,2,4-triazine derivatives. (C) 2004 Wiley Periodicals, Inc.