ChemInform Abstract: Pyridazine Derivatives and Related Compounds. Part 5. Pyrazolo(3,4‐c) pyridazine: Synthesis and Some Reactions.

Abstract

Pyridazine Derivatives and Related Compounds.Part 5. Pyrazolo(3,4-c) pyridazine: Synthesis and Some Reactions.-The pyrazolo(3,4-c)pyridazine (I) is acylated with (II) or alkylated with the phenacyl bromides (IV) to produce the carboxamides (III) or the amino ketones (V). The imines (VII) are prepared from (I) by reaction with the aromatic aldehydes (VI) in refluxing butanol. Cyclocondensation reaction of (I) with acetylacetone (VIII), ethyl cyanoacetate (X), ethyl acetoacetate (XII), diethyl malonate (XIV), the arylidenemalononitriles (XVI), and the ethyl arylidenecyanoacetates (XX) yields tricyclic pyrazoles as outlined in the reaction scheme. The tetracycle (XIX) is synthesized by cyclization of the amino nitrile (XVIIa) with formamide (XVIII). -(DEEB, A.; BAYOUMY, B.; ESSAWY, A. E.-N.; FIKRY, R.; Heterocycles 32 (1991) 5, 895-900; Dep. Chem., Fac. Sci., Univ., Zagazig, Egypt; EN)