The Reaction of 1-Phenylpyrazolidine-3,5-dione with Active Nitriles Using Phase Transfer Catalysis Conditions Technique

Heterocyclization reaction of 1-phenylpyrazolidine-3,5-dione with some active nitriles and acrylonitriles is described. These cyclization reactions afforded novel heterocyclic derivatives such as pyrano[2,3-c]pyrazoles, pyrazolyl-thiazole, pyrazolyl-1,3-thiazines, and pyrazolyl-1,3-oxathiino[6,5-c]pyrazoles. Heating 1-phenylpyrazolidine-3,5-dione alone under phase transfer catalysis conditions afforded the tricyclic dipyrazolofurandione. The structure of the new products has been characterized by IR, NMR, mass spectra, and their elemental analyses.