1: 1.) 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 2.) conc aq. HCl / 1.) benzene, room temperature, 30 min, 2.) 22 h 2: 74 percent / anhydrous potassium carbonate / dimethylformamide / 2.5 h 3: 98 percent / toluene / 0.75 h 4: 49 percent / 10percent aq. HCl / diethyl ether / 25 h View Scheme