formic acid; acetic anhydride T=20 - 25°C; 10 h;

1: 79 percent / dimethylformamide / 3 h / 20 - 25 °C 2: 78 percent / 48percent HBr / H2O; acetic acid / 30 h / Heating 3: 80 percent / HCOOH, acetic anhydride / 10 h / 20 - 25 °C View Scheme

1: 78 percent / 48percent HBr / H2O; acetic acid / 30 h / Heating 2: 80 percent / HCOOH, acetic anhydride / 10 h / 20 - 25 °C View Scheme