Mohamed Mohamed Mohamed Sallam

Reactions with Hydrazonoyl Halides. 31. Synthesis of Some New Pyrrolidino[3,4-c]pyrazolines, Pyrazoles, and Pyrazolo[3,4-d]pyridazines

For part 30 see [1].Received: 29 May 2000; revised form 6 July 2000 / Accepted: 6 July 2000 / Published: 21 July 2000Abstract: Pyrrolidino[3,4-c]pyrazoline and pyrazole derivatives were synthesized via reac-tions of a substituted hydrazonoyl bromide with N-arylmaleimides and active methylene rea-gents, respectively. Synthesized pyrazoles were reacted with hydrazine hydrate to give thecorresponding pyrazolo[3,4-d]pyridazines.Keywords: hydrazonoyl halides, N-arylmaleimides, pyrrolidino[3,4-c]pyrazolines, pyrazoles,pyrazolo[3,4-d]pyridazines.IntroductionHydrazonoyl halides have been widely employed in the synthesis of heterocyclic derivatives [2-5]. Incontinuation of our interest in the synthesis of heterocyclic systems containing a pyrazole moiety [6-10],we report herein a facile synthesis of pyrrolidino[3,4-c]pyrazoline, pyrazole, and pyrazolo[3,4-d]pyridazine derivatives.Results and DiscussionTreatment of the hydrazonoyl bromide 1 [10] with the appropriate N-arylmaleimides 2a-c in benzenecontaining triethylamine afforded pyrrolidino[3,4-d]pyrazolines 3a-c (cf. Scheme 1). The structures ofcompounds 3a-c were confirmed by their spectroscopic data. For example, the

REACTIONS WITH HYDRAZONOYL HALIDES. PART 27[1]: SYNTHESIS OF SOME NEW TRIAZOLO[4,3-a]BENZIMIDAZOLE AND UNSYMMETRICAL AZINE DERIVATIVES

Abstract Triazolo[4,3-a]benzimidazole, unsymmetrical azine containing pyrazole moiety were synthesised via reactions of C-pyrazolôyl-N-p-chlorophenylhydrazonoyl bromide with each 2-(methylthio)benzimidazole and carbodithioates, respectively. Newly synthesised compounds were confirmed on the basis of elemental analysis, spectral data, and alternative route whenever possible.

The Reaction of β-Cyanoethylhydrazine with Diethyl Phenylthiocarbamoylmalonate

Diethyl phenylthiocarbamoylmalonate (2) reacts with β-cyanoethylhydrazin (1) to yield ethyl 3-anilino-2-pyrazolin-5-one (3) via decyanoethylation of the reaction intermediates. Whereas 2 reacts with hydrazine hydrate in refluxing ethanol to yield a mixture of 3-anilino-2-pyrazolin-5-one (4) and the hydrazide (5), the diethyl ester (6) is formed on treatment of 2 with the same reagent in a cooled ethanolic solution. On the other hand, 2 reacts with hydrazine hydrate in the absence of a solvent to yield the carboxylic acid (7). Benzoylacetonitrile reacts with phenylisothiocyanate to yield the thioanilide (8). The latter compound neither reacts with hydrazine hydrate not β-cyanoethylhydrazine.