1.1: 82 percent / pyridine / 18 h / 20 °C 2.1: AgNO3; pyridine / tetrahydrofuran / 3 h / 20 °C 3.1: 78 percent / CrO3; pyridine; Ac2O / CH2Cl2 / 1 h / 15 °C 4.1: 76 percent / p-TsOH / methanol; CHCl3 / 0.08 h / 20 °C 5.1: CeCl3; BuLi / tetrahydrofuran; hexane / 2.5 h / -50 °C 5.2: 85 percent / tetrahydrofuran; hexane / 3 h / -65 °C 6.1: ammonia / methanol / 24 h / 20 °C 7.1: 24.6 g / TBAF / tetrahydrofuran / 4 h / 20 °C View Scheme

1.1: pyridine / 20 °C 2.1: dimethyl sulfoxide; trifluoroacetic anhydride / tetrahydrofuran / 2.75 h / -20 - -15 °C 2.2: 0.33 h 3.1: diethyl ether / 2 h / -78 °C / |Inert atmosphere 3.2: 0.75 h / 20 °C 4.1: pyridine / 1.67 h / 0 °C / |Inert atmosphere 5.1: diethylamino-sulfur trifluoride / 1 h / -20 °C / |Inert atmosphere View Scheme