Synthesis and Antibacterial Activity of New Imidazo[1,2-a]pyridines Festooned with Pyridine, Thiazole or Pyrazole Moiety

Abstract

A series of new 6,8-dichloro-imidazo[1,2-a]pyridine derivatives incorporating pyridine, thiazole, and pyrazole ring systems was synthesized. The synthetic strategy of imidazopyridinyl-pyridine hybrids 2 and 3 involves one pot reaction of the precursor 3-acetyl-6,8-dichloro-2-methylimidazo[1,2-a] pyridine (1) with aldehydes, malononitrile, and/or ethyl cyanoacetate. Treatment of 1 with thiosemicarbazide and/or bromine followed by subsequent cyclization with ethyl bromoacetate, chloroacetone, phenacyl chloride, and/or thiourea was applied as synthetic routes for accessing the imidazopyridinyl-thiazole hybrids 5, 6, and 8–10. The reaction of 1 with dimethylformamide-dimethylacetal followed by subsequent treatment with hydrazine was employed to prepare the imidazopyridinyl-pyrazole motif 12. The antibacterial potency of these imidazopyridine hybrids has been evaluated against some model bacteria. The results indicated that the imidazopyridine-thiazole hybrids revealed remarkable antibacterial activities.

Keywords:

• Imidazo[1,2-a]pyridine
• malononitrile
• thiosemicarbazide
• phenacyl chloride
• ammonium thiocyanate
• antibacterial activity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code (20UQU0039DSR).