An efficient protocol for the synthesis of substituted 5‐amino pyrazole bearing benzo[d]imidazolone Core and their antioxidant activity

Abstract

An efficient, facile and regioselective route has been utilized for the synthesis of novel series of 5-(5-amino-1H-pyrazol-3-yl)-1,3-dimethyl-1,3-dihydro-2Hbenzo[d]imidazol-2-one derivatives (5a-l). The methyl 3,4-diaminobenzoate (1) used CDI/DMF system for the cyclization to benzimidazolone followed by Nmethylation and next ACN/n-BuLi media at À70 C to afford high yielded key intermediate, 3-(1,3-dimethyl-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-5-yl)-3-oxopropanenitrile (4). The final adducts synthesis involved catalytic optimization to generate 5-amino pyrazole-based adducts (5a-l) rather than 3-amino pyrazole (6a-l) are discussed. Chromatographic and spectral techniques ( 1 H & 13C NMR, LC-MS, elemental analysis) confirmed the newly synthesized structures and were evaluated for antioxidant activity using DPPH free radical scavenging assay. The entire compounds showed extra (higher) potency against used standard ascorbic acid except 5j (2-F Ph substituent) while, 5c (ÀEt substitution) was found to be most potent among others.

Design, Synthesis, Molecular Modeling and Biological Evaluation of Novel Pyrazole Benzimidazolone Derivatives as Potent Antioxidants

“…The pyrazoles with a benzimidazole exhibit show various biological and pharmacological activities, including anti-inflammatory [45] and anti-ulcerogenic [43]. Pyrazole derivatives are synthesized using the the1,3-dipolar cycloaddition reaction [46,47] and other methods [48][49][50]. Because of this, various pyrazolebenzimidazole hybrids have gained a reputation as potent antioxidants due to their remarkable effectiveness in combating oxidative stress [51][52][53].…”