Synthesis and antibacterial activity of novel 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide derivatives

The intensely increasing multi-drug resistant microbial infections have encouraged the search for new antimicrobial agents. Hydrazone derivatives are known to exhibit a wide variety of biological activities including anti-microbial. In heterocyclic moiety, imidazo[1,2-a]pyrimidines are the subject of immense interest for their antimicrobial activity and also for their analgesic, antipyretic and anti-inflammatory properties.

Condensation of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide 7 with aromatic aldehydes a-k in ethanol at reflux led to the generation of hydrazone derivatives 8a-k in 80-92% yield. The synthesis of carbohydrazide 7 was accomplished in six steps from commercially available 2-amino pyrimidine. The structures of the synthesized compounds were confirmed by ¹H, ¹³C NMR, Mass and IR spectral data. All the synthesized hydrazone derivatives 8a-k were tested in vitro for their antibacterial activity. Compounds 8d, 8e and 8f exhibited excellent antibacterial activity with zone of inhibition 30-33 mm against E. coli (Gram negative bacteria) and S. aureus (Gram positive bacteria). These compounds also exhibited excellent antibacterial activity with zone of inhibition 22-25 mm against P. aeruginosa (Gram negative bacteria) and S. pyogenes (Gram positive bacteria).

Synthesized and recorded antibacterial activity of some new 5,6,7,8-tetrahydro-imidazo[1,2-a]pyrimidine-hydrazone derivatives.Graphical abstract:Synthesis of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide derivatives.