One‐Pot Multicomponent Synthesis of Novel Substituted Imidazo[1,2‐ a ]Pyridine Incorporated Thiazolyl Coumarins and their Antimicrobial Activity

A series of novel substituted imidazo[1,2‐ a ]pyridine incorporated thiazolyl coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p , 4q , 4r , 4s , 4t ) were synthesized in good yields via one‐pot multicomponent condensation of substituted imidazo[1,2‐ a ]pyridine‐3‐carbaldehyde ( 3a , 3b , 3c , 3d , 3e ), thiosemicarbazide ( 2 ), and substituted 3‐(2‐bromoacetyl)‐2 H ‐chromen‐2‐ones ( 1a , 1b , 1c , 1d )/2‐(2‐bromoacetyl)‐3 H ‐benzo[ f ]chromen‐3‐one ( 1e ) in refluxing ethanol with catalytic amount of acetic acid . All the synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p , 4q , 4r , 4s , 4t ) have been characterized by IR, NMR, and mass spectral studies as well as elemental analyses and evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains. All the compounds displayed moderate antibacterial activity with minimum inhibitory concentration 150 µg/mL, but none of the compounds have shown any antifungal activity.