1: 83 percent / phosphorus oxybromide / 2 h / 150 °C 2: 69 percent / butyllithium; iodine / tetrahydrofuran; hexane / 0.75 h / -75 °C 3: 45 percent / isopropylmagnesium chloride / tetrahydrofuran / 0.75 h / 0 °C 4: 100 percent / zinc; sodium hydroxide / H2O / 2 h / 0 °C View Scheme

phosphorus oxytribromide T=150°C; 2 h;