Abstract

Reaction of 4-acetyl-5,6-diphenylpyridazin-3(2H)-one (1) with diethyl oxalate in refluxing sodium ethoxide/ethanol mixture afforded ethyl 2,4-dioxo-4-(3-oxo-5,6-diphenyl-2,3-dihydropyridazin4-yl)butanoate (2) which with hydrazine hydrate (1:1 mol) in refluxing ethanol afforded ethyl5-(3-oxo-5,6-diphenyl-2,3-dihydropyridazin 4-yl)-1H-pyrazole-3-carboxylate (3) while reaction of 2 with hydrazine hydrate (1:2 moles) in refluxing ethanol gave the corresponding acid hydrazide (4). Reaction of acid chloride (6) with primary amines namely, aniline, p-toluidine and anisidine in the presence of DMF containing K₂CO₃ afforded the corresponding amide derivatives (7a – c). Hydrazones (9a – c) were prepared via the reaction of the acid hydrazide (4) with appropriate aldehydes namely, benzaldehyde, p-chlorobenzaldehyde and p-nitrobenzaldehyde in refluxing ethanol/acetic acid mixture. Reaction of carboxylic acid hydrazide (4) with each of ethyl acetoacetate, acetylacetone and ethyl cyanoacetate gave the corresponding pyrazolone and pyrazole derivatives 11, 12 and 13 respectively.

Key words: Benzilmonohydrazone, pyridazine, pyrazole, ethyl acetoacetate, diethyl oxalate, acetylacetone, ethyl cyanoacetate, antihypertensive, anti-inflammatory.