1: 4-(N,N-dimethlyamino)pyridine / dichloromethane / 8 h / 20 °C 2: boron trifluoride diethyl etherate / dichloromethane / 0.5 h / -78 - -40 °C 3: selenium(IV) oxide / 1,4-dioxane / 14 h / 80 °C 4: pyridine; 4-(N,N-dimethlyamino)pyridine / 1,4-dioxane / 1 h / 20 °C 5: hydrogen fluoride / acetonitrile / 10 h / 50 °C 6: Martin's sulfurane / chloroform / 3 h / 80 °C 7: sodium hydroxide; water / tetrahydrofuran / 1 h 8: selenium(IV) oxide; formic acid / 1,4-dioxane / 1.25 h / 80 °C View Scheme