Synthetic and pharmacological studies on some 1-isonicotinoyl-3-methyl-4-(4-substituted phenyl)-3a,4-dihydro pyrazolo [3,4-c]pyrazoles and their ethoxyphthalimide derivatives

Isoniazid reacted with ethylacetoacetate in absolute ethanol to give 2-isonicotinoyl-5-methyl-2,4dihydro-3H-pyrazol-3-one (1), which upon condensation with various aldehydes (2a-d) afforded the related arylidene derivatives (3a-d).1-Isonicotinoyl-3-methyl-4-(4-substitutedphenyl)-3a,4dihydropyrazolo[3,4-c]pyrazoles (4a-d) were obtained as the result of cyclocondensation reaction between 3a-d and hydrazine hydrate.Subsequently compounds 4a-d were converted to corresponding 2-N-ethoxyphthalimido-6-isonicotinoyl-4-methyl-3-(4-substituted phenyl)-3,3adihydro pyrazolo [3,4-c]pyrazoles 6a-d by the treatment with phthalimidoxyethyl bromide (5).Structures of synthesized compounds were elucidated by means of IR, 1 H NMR and mass spectral data.Final compounds were screened for four biological activities namely "antibacterial, antifungal, antiviral and anticancer".