Synthesis of Novel Pyrazole Tagged Pyridine Derivatives; Their Antimicrobial Activity

Novel pyrazole tagged pyridine derivatives 5a-n are synthesized starting from 3-cyano-4- trifluoromethyl-6- thiophenyl 2(1H) pyridone 1. Compound 1 on hydrolysis followed by decarboxylation resulted in 4-trifluoro-methyl-6- thiophenyl 2(1H)pyridone 2. Compound 2 was treated with POCl3 to get 2- chloro-4-trifluoromethyl-6- thiophenyl pyridine 3; further reaction with hydrazine hydrate resulting in the formation of compound 4. Compound 4 reacted with different substituted 1,3-diketones in ethanol reflux condition to afford pyrazole substituted pyridine derivatives 5a-n. All derivatives were tested against Gram-positive and Gram-negative bacterial strains and different Candida strains by well diffusion method; compounds 5k and 5l showed significant activity. The binding modes of 5k and 5l were also studied by molecular docking studies.