Utility of Enaminonitriles in Heterocyclic Synthesis: Synthesis of Some New Pyrazole, Pyridine, and Pyrimidine Derivatives

The starting (1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)carbonohydrazonoyl dicyanide (2) was used as key intermediate for the synthesis of 3-amino-2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylazo)-[3-substituted]-1-yl-acrylonitrile derivatives (310). In addition, nitrile derivative 2 reacted with hydrazine hydrate or malononitrile to afford the corresponding 3,5-diaminopyrazole 11 and enaminonitrile derivative 13, respectively. On the other hand, compound 3 was subjected to react with malononitrile, acetic anhydride, triethylorthoformate, N,N-dimethylformamide (DMF)-dimethylacetal, thiourea, and hydroxylamine hydrchloride to afford antipyrine derivatives 1621. Moreover, the reaction of enaminonitrile 3 with carbon disulfide in pyridine afforded the pyrimidine derivative 22, whereas, in NaOH/DMF followed by the addition of dimethyl sulphate afforded methyl carbonodithioate 24. The reaction of enaminonitrile derivatives 35 with phenylisothiocyanate afforded the thiopyrimidine derivatives 25ac. Finally, the enaminonitrile 4 reacted with 3-(4-chloro-phenyl)-1-phenyl-propenone to afford the pyridine derivative 27. The newly synthesized compounds were characterized by elemental analyses and spectral data (IR, 13C-NMR, 1HNMR, and MS).