1: tosic acid / benzene / 1 h / Heating 2: 80 percent / I2 / benzene / 4 h / Heating 3: 2.97 g / p-toluenesulfonic acid / benzene / 24 h / Heating 4: 71 percent / DDQ / benzene 5: 85 percent / glacial acetic acid, concd. HCl / 24 h / Heating View Scheme

1: tosic acid / benzene / 1 h / Heating 2: 80 percent / I2 / benzene / 4 h / Heating 3: 2.97 g / p-toluenesulfonic acid / benzene / 24 h / Heating 4: 71 percent / DDQ / benzene 5: 85 percent / glacial acetic acid, concd. HCl / 24 h / Heating 6: 82 percent / Adogen 464, Fremy's salt, KH2PO4 / H2O / 1 h View Scheme

1: tosic acid / benzene / 1 h / Heating 2: 80 percent / I2 / benzene / 4 h / Heating 3: 2.97 g / p-toluenesulfonic acid / benzene / 24 h / Heating 4: 71 percent / DDQ / benzene 5: 85 percent / glacial acetic acid, concd. HCl / 24 h / Heating 6: 82 percent / Adogen 464, Fremy's salt, KH2PO4 / H2O / 1 h 7: 91 percent / NaBH4, O2 / ethanol / 28 h 8: 61 percent / N-bromosuccinimide / dimethylsulfoxide; H2O / 1 h / Ambient temperature 9: 76 percent / potasium tert-butoxide / tetrahydrofuran; 2-methyl-propan-2-ol / 0.5 h / Ambient temperature View Scheme