1: 78 percent / pyridine / dimethylformamide / 4 h / Ambient temperature 2: 67 percent / conc. sulfuric acid / acetic acid / 5 h / 100 °C 3: 72 percent / BBr3 / benzene / 7 h / Heating 4: 85 percent / LiCl, (dimethylamino)pyridine, methanesulfonyl chloride / dimethylformamide / 6 h / Ambient temperature View Scheme

1: 78 percent / pyridine / dimethylformamide / 4 h / Ambient temperature 2: 67 percent / conc. sulfuric acid / acetic acid / 5 h / 100 °C 3: 72 percent / BBr3 / benzene / 7 h / Heating View Scheme

1: 53 percent / pyridine / dimethylformamide / 6 h / Ambient temperature 2: 69 percent / conc. sulfuric acid / acetic acid / 9.5 h / 100 °C View Scheme