Phenacyl Bromides Revisited: Facile Synthesis Of Some NewPyrazoles, Pyridazines and their fused Derivatives
Fathy M. Abdelrazek1*, Hamdi M. Hassaneen1, EkhlassM.Nassar, Anna Jager, Journal of Heterocyclic Chemistry (In press , Accepted ).
Abstract:
Phenacylmalononitriles6a,breact with hydrazines under dry conditions to afford thepyrazole derivatives 7a-d; and in refluxing dioxane to afford the pyridazine-6-iminederivative 8a-d and the pyrazolo[ ]pyridazine derivatives 9a-d. Compound 8a,b weretransformed into their oxo analogues 11a,b upon reflux in ethanolicHCl, while 8c,dwere transformed into the furan derivatives 12a,b under the same reaction conditions (reflux in ethanolicHCl). Compound 6a,bcould be transformed directly into thebenzoyl-pyrazole derivative 14a-d upon coupling with diazotized aromatic amines inpyridine. The structures of the new compounds were substantiated by elementalanalyses and spectral data as well as x-ray crystallographic analysis. Plausiblemechanisms for the unexpected transformations are suggested.
