Synthesis and antimicrobial activity of some novel substituted pyridazin-3(2H)-ones containing 1,3,4-thiadiazole moiety

Abstract

A series of novel 1,3,4-thiadiazol-4,5-dihydropyridazin-3(2H)-ones with expected antimicrobial activity have been synthesized. The synthetic protocol of the target compounds was accomplished by condensing β-aroylacrylic acid 1 with 2,5-diamino-1,3,4-thiadiazole 2 to afford the aza-Michael adduct 3. Subsequently, the obtained adduct 3 was cyclized to 4,5-dihydropyridazin-3(2H)-ones (4a-e) by reaction with selected hydrazines. Furthermore, adduct 3 was also treated with diethylmalonate and ethylacetoacetate to yield 1,3,4-thiadiazolobutanamides 5 and 6, respectively. The later compounds were further reacted with (2 mol) of the hydrazine derivatives to produce substituted thiadiazolopyridazin-3(2H)-ones (7a-c), (9a-c) and (10a-b).