1: triphenylphosphine / toluene / 3 h / Reflux 2: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 0.75 h / 0 - 25 °C 3: boron trifluoride diethyl etherate / 0.5 h / -10 °C 4: hydrogenchloride / ethanol; water / 12 h / 25 °C 5: triethylamine / dichloromethane / 1 h / 0 °C 6: sodium azide / N,N-dimethyl-formamide / 3 h / 80 °C 7: hydrogen / ethanol / 20 °C View Scheme

1: triphenylphosphine / toluene / 3 h / Reflux 2: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 0.75 h / 0 - 25 °C 3: boron trifluoride diethyl etherate / 0.5 h / -10 °C 4: hydrogenchloride / ethanol; water / 12 h / 25 °C 5: triethylamine / dichloromethane / 1 h / 0 °C 6: sodium azide / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme