A green approach for the catalyst-free synthesis of imidazole-bearing pyrazole moiety using PEG-400 as an efficient recyclable medium as potential anti-tubercular and anti-microbial agents

Polyethylene glycol-400 (PEG-400) is a recyclable and rapid reaction medium for synthesizing a new series of 4-(3-[substitutedphenyl]-4,5-dihydro-1-phenyl-1H-pyrazol-5-yl)-1H-imidazoles in two-step procedures by condensation of 1H-imidazole-4-carbaldehyde and various acetophenones to form chalcones followed by base-catalyzed cyclization employing phenyl hydrazine in a catalyst-free approach. The way of projected approach provides easy work-up, less reaction time, avoids metal-based and toxic catalysts, high yield, and reduces the use of carcinogenic organic solvents. The synthesized scaffolds have been screened for their anti-microbial and anti-tubercular activity against a set of pathogens.