1: 82 percent / NaH / tetrahydrofuran; hexamethylphosphoric acid triamide / 12 h / -30 - 20 °C 2: 80 percent / various solvent(s) / 3 h / 213 °C 3: 93 percent / diethyl ether / 0.08 h / -20 °C 4: CF3CO3H / CH2Cl2 / 1 h / 20 °C 5: 2N HCl / methanol; tetrahydrofuran / 3 h / 60 °C View Scheme