1: 5 percent / tetrahydrofuran / 2 h / 20 °C 2: 89 percent / satd. HCl gas in diethyl ether / 0.25 h / 20 °C 3: 100 percent / NaBH4 / methanol / 0.5 h / 0 °C 4: 100 percent / 47 percent hydrobromic acid / tetrahydrofuran / 0.17 h / 20 °C View Scheme

1: 52 percent / tetrahydrofuran / 24 h / 20 °C 2: 82 percent / NaH in mineral oil / dimethylformamide / 1.5 h / 0 °C 3: 26 percent / 97 percent concd. sulfuric acid; silica gel / CH2Cl2 / 1 h / 0 °C View Scheme