1: 53 percent / polyphosphoric acid / 2 h / 100 - 105 °C 2: 48percent aq. HBr, CH3CO2H / 2 h / Heating 3: NaBH4 / ethanol / 0.5 h 4: p-toluenesulfonic acid / benzene / 1 h / Heating 5: pyridine / 3 h 6: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / dioxane / 1 h / Heating 7: K2CO3 / methanol; tetrahydrofuran / 0.5 h / 0 °C View Scheme