1: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) / dioxane / 2 h / Heating 2: 96.2 percent / H2 / PtO2 / ethanol; dioxane / 2 h / 760 Torr 3: 1.) 20percent aq. H2SO4, aq. NaNO2, 2.) H2O / 1.) 0-5 deg C, 15 min, 2.) reflux, 1 h View Scheme

1: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) / dioxane / 2 h / Heating 2: 96.2 percent / H2 / PtO2 / ethanol; dioxane / 2 h / 760 Torr 3: 1.) 20percent aq. H2SO4, aq. NaNO2, 2.) H2O / 1.) 0-5 deg C, 15 min, 2.) reflux, 1 h 4: 87.5 percent / methanol; dioxane; diethyl ether / 1 h / Ambient temperature View Scheme

2,3-dicyano-5,6-dichloro-p-benzoquinone in 1,4-dioxane 2 h; Heating;

1: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) / dioxane / 2 h / Heating 2: 96.2 percent / H2 / PtO2 / ethanol; dioxane / 2 h / 760 Torr View Scheme