2-Quinolone is an organic compound related structurally to quinoline. It is the majority tautomer in equilibrium with 2-quinolinol. The compound can be classified as a cyclic amide, and as such is used as an isostere for peptides and other pharmaceutically inspired targets. The 4-methyl-2-quinolone can be prepared by dehydration of acetoacetanilide.
The isomer 4-quinolone is the parent of a large class of antibiotics called quinolone antibiotics. A prominent example is ciprofloxacin, a broad spectrum antibiotic commonly used for treatment of various infections such as urinary tract infections (UTIs), typhoid, meningitis, gonorrhoea, syphilis, and skin infections.