1: 70 percent / tetrahydrofuran / 0.5 h / -40 deg C -> -10 deg C 2: hydrogen bromide / CH2Cl2 / 0.5 h / 23 °C 3: CH2Cl2 / 18 h / 23 °C 4: 32 percent / n-butyllithium, HMPA / tetrahydrofuran / 1.) -78 deg C, 30 min, 2.) -78 deg C -> -20 deg C, 30 min, 3.) -20 deg C -> 0 deg C, 30 min 5: 1.) potassium carbonate, 2.) lithium hydroxide / 1.) methanol, 25 deg C, 6.5 h, 2.) methanol-water (2:1) 23 deg C, 1 h View Scheme