Synthesis of novel N-triazolo methyl substituted fluoroquinolones and their antimicrobial activity

Abstract

An elegant synthetic strategy was adopted for the preparation of N-triazolo methyl substituted fluoroquinolones 4 and screened for their antimicrobial activity. The synthetic methodology starts from N-propargylation of ethyl 7-chloro-6-fluoro-4-hydroxyquinoline-3-carboxylate (1) followed by reaction with azides through click reaction under Sharpless conditions furnished triazole substituted quinolone ester 3. The latter quinolone esters were reacted with various secondary amines to furnish the corresponding quinolone derivatives 4. Alternatively, quinolone carboxylic derivatives 7a-d were prepared in two steps from triazole tagged quinolone ester. All the final products were screened against various bacterial and fungal strains. Compounds 4a-c and 4k showed moderate antibacterial activity, and 4f showed promising activity against fungal strains.