1: 95.2 percent / chromic acid / Ambient temperature 2: N-bromosuccinimide / CCl4 / 1.17 h / Irradiation 3: NaH / tetrahydrofuran / 3 h / 0 - 20 °C 4: NaH / tetrahydrofuran / 18 h 5: acetic acid, 6 N HCl / tetrahydrofuran; H2O / 2 h / 100 °C View Scheme