1: butyllithium / tetrahydrofuran; hexane / 1 h / 25 °C 2: 71.4 g / sulfuric acid / 5 h / 50 °C View Scheme

phosphorus oxytribromide T=150°C; 0.5 h;

1.1: 77 percent / phosphoric tribromide / 0.5 h / 150 °C 2.1: diisopropylamine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 2.2: 92 percent / tetrahydrofuran; hexane View Scheme