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

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

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