1: 95 percent / CH3CO2NH4 / acetic acid / 0.17 h / Ambient temperature 2: 99 percent / pyridinium hydrobromide perbromide / ethanol / 0.17 h / Ambient temperature 3: 86 percent / 1M BBr3 / CH2Cl2 / 12 h / -20 °C View Scheme

1: glacial acetic acid, conc. HCl / H2O / 72 h / Ambient temperature 2: glacial acetic acid, conc. HCl / H2O / 72 h / Ambient temperature 3: 95 percent / CH3CO2NH4 / acetic acid / 0.17 h / Ambient temperature 4: 99 percent / pyridinium hydrobromide perbromide / ethanol / 0.17 h / Ambient temperature 5: 86 percent / 1M BBr3 / CH2Cl2 / 12 h / -20 °C View Scheme

1: 2,3-dicyano-5,6-dichloro-p-benzoquinone / toluene / 6.5 h / 110 °C / Sealed vessel; Inert atmosphere 2: sodium hydroxide / methanol / 0.33 h / 20 °C 3: sodium sulfide / 1-methyl-pyrrolidin-2-one / 3 h / 160 °C / Inert atmosphere 4: pyridinium tribromide / ethanol / 72 h / 20 °C / Inert atmosphere View Scheme

1: sodium hydroxide / methanol / 0.33 h / 20 °C 2: sodium sulfide / 1-methyl-pyrrolidin-2-one / 3 h / 160 °C / Inert atmosphere 3: pyridinium tribromide / ethanol / 72 h / 20 °C / Inert atmosphere View Scheme

1: sodium acetate; bis(dibenzylideneacetone)-palladium(0) / acetonitrile / 0.17 h / 20 °C 2: 2,3-dicyano-5,6-dichloro-p-benzoquinone / toluene / 6.5 h / 110 °C / Sealed vessel; Inert atmosphere 3: sodium hydroxide / methanol / 0.33 h / 20 °C 4: sodium sulfide / 1-methyl-pyrrolidin-2-one / 3 h / 160 °C / Inert atmosphere 5: pyridinium tribromide / ethanol / 72 h / 20 °C / Inert atmosphere View Scheme