phosphoric acid; water T=170°C; 24 h;

1: 80 percent / bromine / I2 / CH2Cl2 / 20 h / 20 °C 2: 70 percent / dimethylformamide / 24 h / Heating 3: 75 percent / phosphoric acid; H2O / 24 h / 170 °C View Scheme

1.1: n-BuLi / hexane; tetrahydrofuran / 1.5 h / -60 °C 1.2: 80 percent / tetrahydrofuran; hexane / 0.5 h / -60 °C 2.1: 80 percent / bromine / I2 / CH2Cl2 / 20 h / 20 °C 3.1: 70 percent / dimethylformamide / 24 h / Heating 4.1: 75 percent / phosphoric acid; H2O / 24 h / 170 °C View Scheme

1.1: n-BuLi / hexane; tetrahydrofuran / 1.5 h / -60 °C 1.2: 80 percent / tetrahydrofuran; hexane / 0.5 h / -60 °C 2.1: 80 percent / bromine / I2 / CH2Cl2 / 20 h / 20 °C 3.1: 70 percent / dimethylformamide / 24 h / Heating 4.1: 75 percent / phosphoric acid; H2O / 24 h / 170 °C View Scheme

1: 70 percent / dimethylformamide / 24 h / Heating 2: 75 percent / phosphoric acid; H2O / 24 h / 170 °C View Scheme