New thieno[2,3- <i>b</i> ]pyridine-based 1 <i>H</i> -pyrazole hybrids attached to arylazo units: Synthesis of potential MRSA inhibitors
A.A. Ahmed, Sherif M. H. Sanad, Yasser A. Elossaily, Ahmed E. M. Mekky
Abstract
The goal of this work is to examine the impact of integrating arylazo units to the skeleton of thieno[2,3-b]pyridine-based 1H-pyrazoles on their MRSA inhibitory activity. Using a stoichiometric amount of p-toluenesulfonic acid (p-TSA), the new hybrids were obtained by reacting thieno[2,3-b]pyridine-based carbohydrazides with acetylacetone or its aryldiazenyl-containing derivatives. The protocol was carried out in refluxing ethanol for 3–8 h in the presence of three equivalents of p-TSA. Product 4e, connected to phenyldiazenyl and (4-methoxyphenyl)diazenyl units at thieno[2,3-b]pyridine-C5 and pyrazole-C4, respectively, demonstrates the highest antibacterial potency, which exceeds ciprofloxacin with MIC/MBC of 1.8/3.6 µM against S. aureus and E. coli. Moreover, it exceeds linezolid in efficacy with MIC/MBC of 1.8/7.3 µM against MRSA.