γ-cetonitriles 1 react with hydrazine, methylhydrazine and phenylhydrazine in refluxing ethanol to lead to hydrazones 2 which are relatively stable. The cyclization of hydrazones 2 to diaminodihydropyridines 3 , needs longer heating time at higher temperature (>100 °C). The same heterocyclic compounds 3 can be synthesized directly by reacting an equimolecular mixture of hydrazines and γ-cetonitriles 1 in refluxing toluene. On an another hand, the reaction of γ-cetonitriles 1 with hydrazides, thiosemicarbazide, N-phenyl-semicarbazide and ethyl carbazate in refluxing toluene leads to the formation of a variety of triazolodihydropyridines 4. The yields of the formation of the compounds 2, 3 and 4 are good (70 - 85%).
A. Hafidh, H. Zantour, B. Baccar