treatment of 5,8-dihydroxy-1-tetralone (9) with either 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (ddq) in refluxing benzene or silver (i) oxide in refluxing 1,4-dioxane afforded juglone (5-hydroxy-1,4-naphthoquinone) (1) in good yield. with manganese dioxide in dioxane the tetralone gave a mixture of juglone and naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) (3), the proportion of naphthazarin...
