1.1: diphenyl phosphoryl azide; triethylamine / toluene / 21 h / 0 - 80 °C / |Inert atmosphere 1.2: 12 h / |Reflux 2.1: trifluorormethanesulfonic acid / dichloromethane / 12 h / 0 - 20 °C 3.1: hydrogenchloride / 1,4-dioxane / 8 h / 90 °C / |Sealed tube 4.1: nitric acid; sulfuric acid / 12 h / 80 °C 4.2: 12 h / 0 - 20 °C 5.1: dichloromethane / 4 h / 0 °C 6.1: sulfuric acid; sulfur trioxide / 2 h / 60 °C 6.2: 0 - 20 °C View Scheme