An efficient ultrasound-assisted rapid synthesis of 6-bromo-2-substituted-3H-imidazo[4,5-b]pyridine derivatives and their studies on AChE and urease inhibition

Abstract

A rapid and practical protocol was developed for synthesizing 6-bromo-2-substituted-3H-imidazo[4,5-b]pyridine derivatives under ultrasound irradiation for the first time. The protocol employs iminoester hydrochloride, which is highly effective in reacting with 2,3-diamino-5-bromopyridine, resulting in products with good yields and facilitating easy work-up in short reaction times. This method proved to be more efficient than others in terms of green chemistry. The inhibitory properties of all synthesized compounds against urease and acetylcholinesterase were evaluated. Among all newly synthesized compounds, 6(5)-bromo-2-(4-chlorobenzyl)-3H-imidazo[4,5-b]pyridine (2d) exhibited the best inhibitory activity, with an IC50 value of 9.00 ± 0.10 µg/mL against AChE. 6(5)-Bromo-2-(4-nitrobenzyl)-3H-imidazo[4,5-b]pyridine (2 g) has the best inhibition result with 15.85 ± 0.05 µg/mL IC50 value against urease.