S. Shroff, S. K. Mishra, P. Mohanta
Aug 12, 2022
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Organic Preparations and Procedures International
Abstract
The piperazine unit is common among numerous effective drugs in the market. 1,2 Piperazinyl linked ciprofloxacin dimers, for example, are reported as potent antibacterial agents against resistant strains of Staphylococcus aureus. 3 1,4-Disubstituted piperazines have been observed as antagonist-based HIV-1 entry inhibitors. 4 Indolylpropyl benzami-dopiperazines act as ligands of acetylcholinesterase and serotonin transporters and are used as therapeutics against Alzheimer ’ s disease. 5 The compound SIPI5047 shows sig-nificant in vivo analgesic activities similar to morphine. 6 Flunarizine is used as a calcium channel blocker to prevent chronic inflammatory pain. 7 Piperazine moieties are also present in antibiotic drugs, 8 antifungals 9 , anxiolytics, 1 antidepressants, 11 and anti-psychotic drugs. 12 Of particular interest, piperazinyl derivatives have demonstrated enhanced antimicrobial activities against a panel of drug resistant pathogenic bacterial strains. 13,14 This background of successful discoveries motivated us to explore the preparation and preliminary antimicrobial assessment of N-aryl-4-(4-methyl-piperazine-1-ylmethyl)benzamide derivatives (Scheme 1, compounds 4a - j ). The target piperazinyl benzamides 4a-j were prepared in a straightforward sequence using 4-methylbenzoic acid ( 1 ) as the ultimate precursor. Benzylic bromination of 1 with N-bromosuccinimde produced 4-bromomethylbenzoic reaction (cid:1) The progress of the reaction The reaction mass was cooled to 0-5 (cid:1) C and stirred for 1 hr at the same The solid thus obtained was filtered and washed with chilled dichloromethane. Water was added to the filtrate and stirred for 30 min at 25-30 (cid:1) C and the layers were separated. The organic layer was dried over sodium sulfate, filtered and evaporated under vacuum at 45-50 (cid:1) C to a was crystallized from ether to acid 2, 92%, mp , 1 2941, z