4-nitroso-1-phenyl-3-methyl-2-pyrazolin-5-one in the synthesis of: Some new 4-substituted heterocycles of pharmaceutical interest

Condensation of 4-nitrosopyrazolone 1 with active methylene components namely, malononitrile, acetophenone, ω-cyano-acetophenone and i or 1,3-diphenylacetone gave compounds 2a-c and 4. Treatment of 2a, b with hydrazine hydrate gave the aminopyrazoles 3a,b. Reaction of 1 with some hydrazines afforded derivatives 5,6,7a, b. While the condensation of 1 with hydrazine hydrate gave the bispyrazolone 8. The structures of the ring systems have been confirmed by their I R, ¹H-NMR and mass spectral data.