1: boron trifluoride diethyl etherate / 17 h / 0 - 20 °C 2: sulfuric acid / ethanol / 16 h / 78 °C 3: sodium carbonate / 0.5 h / 20 °C / pH 6.5 - 7 4: sodium azide / water; ethanol / 24 h / |Reflux 5: triphenylphosphine; acetic acid / water; tetrahydrofuran / 16 h / 45 °C View Scheme

1: boron trifluoride diethyl etherate / 17 h / 0 - 20 °C 2: sulfuric acid / ethanol / 16 h / 78 °C 3: sodium carbonate / 0.5 h / 20 °C / pH 6.5 - 7 4: sodium azide / water; ethanol / 24 h / |Reflux 5: triphenylphosphine; acetic acid / water; tetrahydrofuran / 16 h / 45 °C 6: phosphoric acid / water; ethyl acetate; ethanol / 50 - 55 °C View Scheme

1: boron trifluoride diethyl etherate / 17 h / 0 - 20 °C 2: sulfuric acid / ethanol / 16 h / 78 °C 3: sodium carbonate / 0.5 h / 20 °C / pH 6.5 - 7 4: sodium azide / water; ethanol / 24 h / |Reflux 5: 5 Pd/C; hydrogen / ethanol / 3 h / 24 °C View Scheme

1: boron trifluoride diethyl etherate / 17 h / 0 - 20 °C 2: sulfuric acid / ethanol / 16 h / 78 °C 3: sodium carbonate / 0.5 h / 20 °C / pH 6.5 - 7 4: sodium azide / water; ethanol / 24 h / |Reflux View Scheme