1: toluene-4-sulfonic acid / toluene / 120 °C 2: water; potassium hydroxide / ethanol / Reflux View Scheme

1: 95.3 percent / bromine / CHCl3 / 2 h / Ambient temperature 2: 51.6 percent / sodium hydride, cuprous iodide / dimethylformamide / 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 15 h 3: 82.1 percent / manganese dioxide / CH2Cl2 / 72 h / Ambient temperature View Scheme

1: 95.3 percent / bromine / CHCl3 / 2 h / Ambient temperature 2: 51.6 percent / sodium hydride, cuprous iodide / dimethylformamide / 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 15 h 3: 82.1 percent / manganese dioxide / CH2Cl2 / 72 h / Ambient temperature 4: 64.5 percent / Claisen's alkali / 0.5 h / Heating View Scheme

1-n-butyl-3-methylimidazolium hexafluorophosphate; trichlorophosphate T=90 - 100°C; Bischler-Napieralski cyclization; 1 h;

1: 79 percent / P2O5; POCl3 / toluene / Heating 2: 89 percent / NaBH4 / ethanol 3: 86 percent / aq. HBr / Heating View Scheme