Abstract The 5H-pyrido [2, 3-a] phenoxazin-5-one derivatives and 5H-pyrido [3, 2-a] phenoxazin-5-one derivatives were prepared by the condensation of substituted 2- aminophenols with 6, 7-dibromo-5, 8-quinolinequinone followed by dehalogenation in the presence of sodium hydrosulfite dissolved in aqueous pyridine under a nitrogen atmosphere.