1.1: triphenylphosphine / ethanol / 0.33 h / 0 °C 1.2: 3 h / 0 - 20 °C 1.3: 3 h / Reflux 2.1: triethylamine / dichloromethane; water / 0.5 h / 0 °C 3.1: boron trifluoride diethyl etherate / 1.5 h / -8 °C 4.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / ethyl acetate / 1 h / 0 °C 5.1: sodium hydride / tetrahydrofuran / 1 h / 20 °C 6.1: sodium azide; lithium chloride / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme