Synthetic and biological studies on some fused pyrazoles and their ethoxyphthalimide derivatives

Ethylacetoacetate reacts with nicotinohydrazide in absolute ethanol to give 5-methyl-2-(pyridin-3-ylcarbonyl)-2,4-dihydro-3H-pyrazol-3-one 1 which upon condensation with various aryl aldehydes affords the related arylidene derivatives 3a-d. Cyclisation reaction between hydrazine hydrate and compounds 3a-d yields 1-nicotinoyl-3-methyl-4-(4-substituted phenyl)-3a,4-dihydro pyrazolo[3,4-c]pyrazoles 4a-d. Subsequently title compounds 6a-d are obtained by reaction between compounds 4a-d and phtalimidoxyethyl bromide 5 in presence of base. Final compounds have been screened for various cell cultures of antimicrobial and antiviral testing with various expand standard drugs.