Synthetic Studies on N-Methyl Piperazine Containing Pyrazoles and Their Ethoxyphthalimide Derivatives

Abstract

In the present investigation, synthesis of 1-{4-[5-aryl-1-(N-ethoxyphthalimido)-4,5-dihydro- 1H-pyrazol-3-yl]-2-nitrophenyl}-4-methyl-piperazine (6a-d) via a series of reactions was carried out. For this purpose 4-N-methyl piperazinyl-3-nitro acetophenone (2) was prepared by the nitration of 4-chloroacetophenone, followed by addition reaction with N-methyl piperazine in isopropanol, which on condensation with various aldehydes (3a-d) gave 3-aryl-1-[4-(4-methylpiperazin-1-yl)-3-nitrophenyl]prop-2-en-1-one (4a-d). Arylidine derivatives (4a-d) were further cyclized to their corresponding pyrazole derivatives (5a-d) by reaction with hydrazine hydrochloride in DMF. Furnished the final compounds (6a-d) through subsequent treatment of 1-{4-[5-aryl-4,5-dihydro-1H-pyrazol-3-yl]-2-nitrophenyl}-4-methylpiperazine (5a-d) with N-hydroxyphthalimide in the presence of NaH in DMF. All the synthesized compounds have been characterized by elemental analysis and spectral data.