Reactions of quinoxalin-2-one with β-diketones: a new approach to 6a,7-dihydro-5H-pyrido[1,2-a]quinoxaline-6,8-diones

Quinoxalin-2-one on heating with acetylacetone, benzoylacetone or heptane-3,5-dione in trifluoroacetic acid gives 6a,7-dihydro-5 H -pyrido[1,2- a ]quinoxaline-6,8-dione derivatives.